I don’t know about your coworker, but on your elicenser, if you bought a Version 9.5 upgrade from 8.5, the 8.5 license will no longer appear on that elicenser or in your account. It will only show the Version 9.5 license. But that Version 9.5 license will still let you use Version 8.5 and 9.5 (even simultaneously) on the computer the elicenser is plugged in to.
There’s no reason I know of to put 2 full version licenses on one elicenser (not sure it’ll even let you do that). Because the Version 9.5 license also covers all previous versions.