I am a crew member with a LARP system. When I'm playing a minor NPC who isn't very important to the wider plot, I have some fairly standard and basic kit that I just throw on. If I'm a labourer, I've got a plain boiler suit. If I'm some kind of background soldier, I've got a standard set of armour to wear.
Sometimes, though, player action takes one of those mooks and makes them important. To give a concrete example, one character I played needed to walk down a road at a scheduled time carrying an interesting and exciting package. The character did have some brief, but it boiled down to "you don't know anything useful about the box, you're just doing your job". The players were expected to steal the package and not really bother too much about me. Instead, the players captured me, told me that they really needed to know who was sending these packages, and paid me a significant sum of hush money. They told me to complete the delivery, head back to my office, then keep my ear to the ground for as much information as I could find about these people.
Thus did Jim the Courier ascend from "faceless mook" to "valuable undercover informant".
This is awesome. The game masters thought that this was awesome. They're rolling with it, and the players are loving the fact that their in-character decisions have given them a new and interesting plot thread to pull. Unfortunately, that character looks like every other faceless character that I play. Now, when I turn up in my generic kit, they'll occasionally greet me and say "Ah, it's Jim the Courier!", and I'll have to correct them. Whilst not game-breaking, this is inconvenient.
If I give Jim the Courier a bunch of fresh costume so he looks different, they're unlikely to recognise him and would rightly be suspicious. If I keep using this same basic costume, other characters will start getting mixed up.
How can I handle signalling the difference between Jim the Courier and a generic kit with this development? Should I change Jim's appearance, and if so how?