Well... I can pimp this bug report with replays, screenshots and what else.. I'm not going to do this.. Just;

Take two cars (I tested with GTR and LX4 cars)
Start to make car contact with the other car on the back of the bumper, side or any place you like
ISP_CON appears
Continue "ramming"
One or more ISP_HLV are generated with a wall flag for one of the PLIDs, while there is no wall/barrier

This was tested with PRISM, CInsim and Insim sniffer.

Thanks for the attention

Roger