Leave to remain for 6 months twice??

I'm from canada and I lived in Wiltshire for 2 years under the youth mobility visa which expired at the beginning of 2016. I've come back to stay for 6 months without a visa and got a stamp in my passport at Gatwick that says "leave to remain for 6 months" buuut my boyfriend and I just went to amsterdam for 2 nights and when we came back into bristol I got another stamp in my passport that says "leave to remain for 6 months" again??? they did ask me a million questions and made me prove that I have a flight home in August (which would be at the end of the original 6 months). So, does anyone have any experience with this or know whether or not that actually allows me another 6 months or will it be a drama next time i come back?

thaaaank you!!