temping question

Temping question. I have been using a regular thermometer for about 2 weeks. I just got my bbt. This morning I took it and it is significantly different from the regular thermometer. I'm talking by a degree almost 2. What should I do? I am on CD 6. Period is just ending. Should I just start over using bbt. Continues regular the rest of this cycle or just switch to bbt and keep old temps even if it creates a huge drop which isn't ovulation?