Hi Aarti,
this behaviour is a new feature. Please see Note 2137273. https://launchpad.support.sap.com/#/notes/2137273
So you need to build up a scenario for testing your plain converter during runtime. In your converting channel you need to maintain the parameter appendSeqNumToDupSetas "true" to append the sequencing numbers and "false" for not appending the sequencing numbers.
Unfortunately there is currently no checkbox in b2bic for switching this appending of sequencing numbers on or off, so in you need a test scenario for runtime testing. Per default it is set as false during runtime, however you can maintain this parameter like this:
Kind regards
Konrad
