Camera set to RAW only but saving JPGs

I've just returned from a trip and have about 1700 photos on my SD card. Roughly 1200 are RAW format and 500 are JPG. This is weird because my camera is set to RAW only. I am using an a6600.

Some of the JPGs seem to be duplicates of RAWs I shot using burst mode and have the same file numbers (eg DSC01234.ARW and DSC01234.JPG are both the same pic of a swan).

Others JPGs have a file number which isn't replicated in the list of RAW files. (Eg a pic of my partner is DSC01440.JPG and there is no DSC01440.ARW)

I'm stumped, can anyone help me understand what's going on here?