When looking at a computer's Resource Change History (right-click on computer > CMDB Functions > Resource Change History), it's observed that the resource audit history only shows the last user to make a change and not all users.
ITMS 8.6 +
Product working as designed
This was done on purpose. This is because usually customers have millions of resources, that are changed quite often by inventory from clients, AD import etc. That was leading to Inv_Audit table growing too big - hundreds of millions rows. By default - only last change is being saved.