Preg test line fainter than first test.

Hello hello, this is my first time posting and I have been ttc for 2 years. I have done two pregnancy tests and both have come back positive, but the second one, which was using FMU seems to be lighter than first one done 10 hours earlier. Is this normal? I was always told FMU contained the highest level of HCG. My periods are irregular and long but the first day of my last period was May 18th and I know I concieved on June 7th which puts me at about 6 weeks and 5 days. This is also my first time being pregnant.

Thank you for your help :-)