Indent/False Positive Question

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So, I know that FRERs have been common with getting indents and false positives lately. I haven’t gotten any myself because I haven’t been using them, but I was thinking after seeing a comment on someone’s test:

If you got a false positive or what you thought would be a positive, did you know it was false because it didn’t get any darker or did AF show?

Because I would assume because it was a false positive, taking another test would prove that the first was wrong especially if it’s been a couple days and no change (say you get another false positive). If it gets darker and af shows, then it was most likely a chemical.

This may be a dumb question and I could just be generally overthinking everything but I’m gonna test again in the morning (not with an FRER) so I’m just thinking “aloud” about random stuff.