Tax posted in 2 lines

Hi all,

Could anyone tell me, what triggers the posting of 2 lines to the tax account (19126 in this example)?

FTXP has only 1 account maintained. I'm simulating the same posting on a different server and there only 1 line is mentioned:

For some reason in the second example (which we want) is mentioned in one line. The net amount is the same in both examples, but we want to have only 1 line.

Thanks for your help in advance,

Alexis