Faint positive dilemma

Yesterday, I went to the doctors to get my ears cleaned out- I had swimmers ear. I was also going to talk about birth control, so they did a urine test. After forever, they come and tell me that two tests have a faint positive, and two are negative. I had no idea as I just had my period july 17. And I haven’t had sex since July 12.

My at home pregnancy tests are negative. I saw the positives at the doctors office. I got bloodwork done today. But has anyone heard of anything like this? Testing positive at a doctors office, but negative at home? I did first response digital and non digital, plus Walmart brands. I don’t understand. Obviously I am fully aware I could be having a chemical, but keep the dates in mind.