How do I stop pathfinding enemies from merging

Hello

i am currently working on a prototype form a top down zombie game. I have lots of different enemies chasing the player but after a while they all join together to end up looking like one enemy. I was wondering if anyone had a simple solution. However i have come up with one idea to stop it happening which would be to have the enemies at slightly different rotation speeds that could stay the same from the start or change whilst the game goes on (using variables and repeat loops). I hope this helps people if it works and please tell me if there is a simple solution that i have missed.

ps: adding the enemy as a pathfinding object does not work.

thanks

A fix i thought of as a temp would be to add a randomiser in the pathfinding speed, this meant that if the zombies were one theyll quickly sperate