If you call this with argument "unused=true" it searches for the translation strings that exist in en_US but are never used.
IMPORTANT: that can take quite a lot of time (up to 10 minutes), you need to tune the max_execution_time on your php.ini accordingly.

Duplicate strings in lang files in /home/wisweb/public_html/management/dev/translation/../../htdocs/langs/en_US/ - 82 found

#StringFile and lines
29InvoiceSubtypebills.lang (671 - Invoice Subtype)
main.lang (1298 - Invoice subtype)
37AccountancyCodecompanies.lang (300 - Accounting account)
main.lang (894 - Accounting Code)
62IncotermLabelincoterm.lang (3 - Incoterms)
main.lang (1005 - Incoterms)
64LinkANewFilelink.lang (2 - Link a new file/document)
main.lang (1287 - Link a new file/document)
65LinkedFileslink.lang (3 - Linked files and documents)
main.lang (1288 - Linked files and documents)
66NoLinkFoundlink.lang (4 - No registered links)
main.lang (1289 - No registered links)
67LinkCompletelink.lang (5 - The file has been linked successfully)
main.lang (1290 - The file has been linked successfully)
68ErrorFileNotLinkedlink.lang (6 - The file could not be linked)
main.lang (1291 - The file could not be linked)
69LinkRemovedlink.lang (7 - The link %s has been removed)
main.lang (1292 - The link %s has been removed)
70ErrorFailedToDeleteLinklink.lang (8 - Failed to remove link '<b>%s</b>')
main.lang (1293 - Failed to remove link '<b>%s</b>')
71ErrorFailedToUpdateLinklink.lang (9 - Failed to update link '<b>%s</b>')
main.lang (1294 - Failed to update link '<b>%s</b>')
72URLToLinklink.lang (10 - URL to link)
main.lang (1295 - URL to link)
3IdModuleadmin.lang (136 - Module ID)
modulebuilder.lang (2 - Module id)
4NoticePeriodadmin.lang (288 - Notice period)
holiday.lang (126 - Notice period)
5LanguageFileadmin.lang (396 - Language file)
modulebuilder.lang (57 - File for language)
6PriceFormatInCurrentLanguageadmin.lang (439 - Price Format In Current Language)
companies.lang (33 - Price display format in the current language and currency)
7Module62000Nameadmin.lang (728 - Incoterms)
incoterm.lang (1 - Incoterm)
8Module62000Descadmin.lang (729 - Add features to manage Incoterms)
incoterm.lang (2 - Add features to manage Incoterm)
9Upgradeadmin.lang (1191 - Upgrade)
install.lang (101 - Upgrade)
10Serveradmin.lang (1202 - Server)
install.lang (46 - Server)
11DatabaseServeradmin.lang (1204 - Database host)
install.lang (49 - Database server)
12DatabaseNameadmin.lang (1205 - Database name)
install.lang (50 - Database name)
13DriverTypeadmin.lang (1213 - Driver type)
install.lang (45 - Driver type)
14Buyadmin.lang (1872 - Buy)
products.lang (56 - Purchase)
15Selladmin.lang (1873 - Sell)
products.lang (55 - Sell)
16CashDeskadmin.lang (1909 - Point of Sale)
cashdesk.lang (3 - Point of sale)
17ByDefaultInListadmin.lang (2085 - Show by default on list view)
categories.lang (99 - By default in list)
1LineIdaccountancy.lang (145 - Id line)
exports.lang (44 - Id of line)
2CustomerInvoicePaymentaccountancy.lang (251 - Payment of invoice customer)
banks.lang (107 - Customer payment)
18AffectedToagenda.lang (10 - Assigned to)
projects.lang (124 - Allocated to)
19Locationagenda.lang (14 - Location)
stocks.lang (37 - Location)
20ReceptionClassifyClosedInDolibarragenda.lang (70 - Reception %s classified closed)
receptions.lang (50 - Reception %s classified Closed)
21InterventionSentByEMailagenda.lang (88 - Intervention %s sent by email)
interventions.lang (48 - Intervention %s sent by email)
22DeleteTypeassets.lang (20 - Delete)
members.lang (99 - Delete)
23ShowTypeCardassets.lang (23 - Show model '%s')
members.lang (169 - Show type '%s')
24IBANbanks.lang (32 - IBAN number)
bills.lang (498 - IBAN)
25BICbanks.lang (33 - BIC/SWIFT code)
bills.lang (503 - BIC/SWIFT)
26SubscriptionPaymentbanks.lang (109 - Subscription payment)
members.lang (183 - Contribution payment)
27InvoiceRefbills.lang (366 - Invoice ref.)
receiptprinter.lang (72 - Invoice ref)
28Salariesbills.lang (670 - Salaries)
salaries.lang (7 - Salaries)
30NoSupplierOrderboxes.lang (83 - No purchase order recorded)
orders.lang (87 - No purchase order)
31ShowCompanycashdesk.lang (32 - Show company)
companies.lang (316 - Third Party)
32Historycashdesk.lang (74 - History)
suppliers.lang (8 - History)
33DeleteFromCatcategories.lang (88 - Remove from tags/category)
compta.lang (294 - Remove from accounting group)
34Customercommercial.lang (4 - Customer)
companies.lang (254 - Customer)
35Prospectcommercial.lang (6 - Prospect)
companies.lang (252 - Prospect)
propal.lang (12 - Prospect)
36ShowTaskcommercial.lang (19 - Show task)
projects.lang (41 - Show task)
38ContractStatusClosedcontracts.lang (9 - Closed)
products.lang (88 - Closed)
39MinimumAmountdonations.lang (27 - Minimum amount is %s)
members.lang (215 - Minimum amount of membership payment (has priority on any default amounts))
40NewSubscriptioneventorganization.lang (121 - Registration)
members.lang (79 - New contribution)
41ExportsAreaexports.lang (2 - Exports)
other.lang (296 - Exports area)
42ExportableDatasexports.lang (6 - Exportable dataset)
other.lang (300 - Exportable data)
43AvailableFormatsexports.lang (28 - Available Formats)
other.lang (297 - Available formats)
44ChooseFileToImportexports.lang (67 - Upload file then click on the %s icon to select file as source import file...)
stocks.lang (252 - Upload file then click on the %s icon to select file as source import file...)
45ExternalSiteSetupexternalsite.lang (2 - Setup link to external website)
other.lang (327 - Setup link to external website)
46ExternalSiteURLexternalsite.lang (3 - External Site URL)
other.lang (328 - External Site URL of HTML iframe content)
47ExternalSiteModuleNotCompleteexternalsite.lang (4 - Module ExternalSite was not configured properly.)
other.lang (329 - Module ExternalSite was not configured properly.)
48ExampleMyMenuEntryexternalsite.lang (5 - My menu entry)
other.lang (330 - My menu entry)
49FTPClientSetupftp.lang (2 - FTP Client module setup)
other.lang (332 - FTP or SFTP Client module setup)
50NewFTPClientftp.lang (3 - New FTP connection setup)
other.lang (333 - New FTP/SFTP connection setup)
51FTPAreaftp.lang (4 - FTP Area)
other.lang (334 - FTP/SFTP Area)
52FTPAreaDescftp.lang (5 - This screen shows a view of an FTP server.)
other.lang (335 - This screen shows a view of an FTP et SFTP server.)
53SetupOfFTPClientModuleNotCompleteftp.lang (6 - The setup of the FTP client module seems to be incomplete)
other.lang (336 - The setup of the FTP or SFTP client module seems to be incomplete)
54FTPFeatureNotSupportedByYourPHPftp.lang (7 - Your PHP does not support FTP functions)
other.lang (337 - Your PHP does not support FTP or SFTP functions)
55FailedToConnectToFTPServerftp.lang (8 - Failed to connect to FTP server (server %s, port %s))
other.lang (338 - Failed to connect to server (server %s, port %s))
56FailedToConnectToFTPServerWithCredentialsftp.lang (9 - Failed to login to FTP server with defined login/password)
other.lang (339 - Failed to login to server with defined login/password)
57FTPFailedToRemoveFileftp.lang (10 - Failed to remove file <b>%s</b>.)
other.lang (341 - Failed to remove file <b>%s</b>.)
58FTPFailedToRemoveDirftp.lang (11 - Failed to remove directory <b>%s</b>: check permissions and that the directory is empty.)
other.lang (342 - Failed to remove directory <b>%s</b>: check permissions and that the directory is empty.)
59FTPPassiveModeftp.lang (12 - Passive mode)
other.lang (343 - Passive mode)
60ChooseAFTPEntryIntoMenuftp.lang (13 - Choose a FTP site from the menu...)
other.lang (344 - Choose a FTP/SFTP site from the menu...)
61FailedToGetFileftp.lang (14 - Failed to get files %s)
other.lang (345 - Failed to get files %s)
63CreateUserinstall.lang (56 - Create user account or grant user account permission on the Dolibarr database)
users.lang (31 - Create user)
73CreatedByother.lang (129 - Created by %s)
ticket.lang (169 - Created by)
74Stockproducts.lang (51 - Stock)
stocks.lang (18 - Stock)
75Stocksproducts.lang (53 - Stocks and location (warehouse) of products)
stocks.lang (19 - Stocks)
76Movementsproducts.lang (54 - Movements)
stocks.lang (28 - Movements)
77Suppliersproducts.lang (93 - Vendors)
suppliers.lang (2 - Vendors)
78Unitproducts.lang (182 - Unit)
stocks.lang (44 - Unit)
79ContractSignedpropal.lang (95 - Contract signed)
recruitment.lang (48 - Contract signed)
80WithdrawalReceiptsalaries.lang (32 - Credit transfer order)
withdrawals.lang (12 - Direct debit order)
81OrderWaitingsalaries.lang (33 - Pending order)
withdrawals.lang (94 - Waiting for treatment)
82NewUserticket.lang (305 - New user)
users.lang (30 - New user)