Well the thing is, I've sent paint chips I had "1" of, only for them to go to "0", but I can keep sending them. This is how I discovered having more then 1 listing for a paint chip, and no, they don't get listed side-by-side either, so that makes it even harder to catch.
Even if you sort by hue, they don't get listed in the same order, if that's what you're thinking.
Most likely this. I've had 1 of a particular chip, painted a car, and then still had 1 of that particular chip. It seems to do weird things if you've got the same chip split over multiple entries.
I've had it go from:
<chip name> 1
<chip name> 2
Using the 1 paint chip, not one of the two, to:
<chip name> 1
<chip name> 1
It's actually even funnier for suits and helmets if you're using the ones that came as part of the DLC and could be won prior. It allows you to turn tradable items into non-tradeable, and the other way around.
I've had this happen:
<helmet (non-tradable)> 1
<helmet (tradable)> 2
Now delete the non-tradable one, refresh, and now you've got:
<helmet (non-tradable)> 1
<helmet (tradable)> 1
Not good, but, it also works the other way around.
<helmet (non-tradable)> 1
<helmet (tradable)> 1
Delete the tradable, and you've got left:
<helmet (tradable)> 1
Go figure. Didn't try to reproduce it on a grand scale, but that's how it worked for me.