What are the chances of getting 2 coloured evap lines on first response tests?

I've done 2 tests - the first I didn't manage to check within the time frame (checked about 30 minute mark) and there was a 2nd pink line

The second test was done a few days later (not with FMU). I think it was actually under-saturated because it took over a minute for the urine to pass through the window and about a minute or two for the control line to even show up followed by a very faint second line...

I've spent some time googling and apparently first response have had a bad batch of tests recently that are showing a lot of evap lines (some being coloured, according to some people who have used them)

I'm going to test again tomorrow morning with just an internet cheapie test that I have in the cupboard but just wanted others opinions...