From watching the ASOP documentary years ago it seems they were all recorded in the same session as they were working on 16 songs (15 we know and the kinda infamous at this point missing song) and there was one bit where Anders was working on Eraser and he described it to the camera as a bit more of an old school track. The different production I don't know, all 4 tracks on the mirrors truth ep sound different and have different listed production teams. I think they were just trying to settle on a mix for the album possibly. Eraser sounds the best of the ASOP sessions, if the whole album was mixed like it then it would have been a shade better.