Positive pregnancy test at 8 week pp

Mary-Ashley • I have 2 beautiful baby girls and a wonderful husband

So like a dummy my bf and I had unprotected sex multiple times 5 weeks after having my daughter. And tonight I took 2 pregnancy test (I am now 8 weeks pp) and they both came up positive. Could this just be a result of leftover hcg levels from my last pregnancy or is it a new pregnancy??