Hello my girlfriend took two home pregnancy tests and both came back positive but she has the nexplanon implant, could it be a false positive?

Probably not false: Nexplanon failures are VERY rare unless it was placed when someone was already in early pregnancy. If she has a positive pregnancy test then she needs to see a doctor for confirmation. A false positive seems unlikely if both tests are positive.

See below: Please see the gynecologist asap and have them evaluate your girlfriend. She may need serum BHCG levels checked to further evaluate this.