Steps to reproduce / test case
Description:
When using the option -idbased with lrelease message elements should be identified with the id attribute and not with the source translation. Currently if the ID is different, but source is the same, then only one of the message elements are included into the .gm file.

Steps:

• lrelease attached id-based.ts file with -idbased option

Actual result:

• "Warning: dropping duplicate messages in 'id-based.qm'" is given

Expected result:

• The .gm file is generated without warnings. Both message elements are included to the .gm file.