disable multiple account assignment in one line item

Hello experts,

In standard SRM shopping carts and POs, there's a possibility of distributing the costs to multiple (more than one) account assignment categories in one line item by clicking the Add button under account assignment tab..

Is there any way to disable this functionality in SRM  via customizing or at least disable the button that lets the user add a second accounting line?

We are running extended classic with srm713.

Any input is greatly appreciated.

Regards,
Dex