Depends on your transfer method.
If you transfer audio by playing the DP03 and re-recording onto the DP24, you're limited by the no. of physical audio outputs on the DP03 (the DP24 can record up to 8 tracks if the DP03 could provide them).
If you use the higher quality method to copy individual files between SD-cards, you can export multiple tracks in one go on the DP03, then copy the files from the DP03 WAVE directory into the DP24 AudioDepot folder, then import the files into tracks on the DP24. The import process can only handle one track at a time though (it could be a stereo track so if the DP03 tracks are stereo, you'd only need 4 imports instead of 8 - update: just checked DP03 manual and it seems you cannot export tracks as stereo, only the master track).
Make sure the current song is created with the correct format to match the DP03, i.e 16 bit, 44.1K otherwise it won't be able to import the files.