The 'new' blobs format (not that new now) in CWM and Philz (and other CWM based recoveries) differs in that it's incremental so you'll only ever have one blobs folder. This is referenced by the backups you have listed in the backups folder. Think is was done to cut down on space. You can change the format to something else in Philz's not sure about CWM - flashed Philz's ages ago to minimise SDS risk.
So your AOKP backup is there, nothing wrong with it'll be listed in the backups folder, along with any other backups you took via CWM using the blobs format.
TWRP uses a different format and creates a separate backup folder and files for each backup. Just be aware - don't try and restore a backup made with a different recovery than the one you're currently using.
Edit: not sure so I'd check that TWRP has been updated with kernel source fix to minimise SDS risk. Check the xda sticky post by rootSU in the S3 general forum.