OPK - False High?

Hi all!

This is my first month TTC since having my implant removed earlier this month. I have been taking OPK strips at the chance that I would ovulate before AF arrived but all have been negative and fairly low until this evening.

The test line came up dark quite quickly and I was so shocked so I tested again from the same urine sample. However, the second test (the first one in the picture) is no where near as dark as the first.

Could the first test have been a false high? Has anyone else experienced this?

Thank you in advance x