The short answer is no.
The long answer is that each CD, when loaded with a USB drive connected, will save analysis information to the USB drive, with an incrementally named/numbered file for each disc you load - the first disc is gets a file named CDJ00001.PDJ, the second is CDJ00002.PDJ, etc. In addition to these files, there is an index file which allows the CDJ to match the unique ID code for each CD to the associated file. If you were to try and take the indexes from two USB drives and merge them, the first problem you'll encounter is overlap on the files - each USB will have a CDJ00001.PDJ file, but they're both different in terms of content.
So let's say you have 100 CDs indexed on one player and 100 on the other and neither have overlap; you could, theoretically, batch-rename them to start after the end of the first list; USB drive A would have 1-100 and drive B would have 1-100, but you rename those 101-200. You'd need to also edit the index file so the data there matches the files, then you'd have to merge the index file data from drive B with drive A. That's great and all, but in reality, there's good odds that you've loaded the same CD into both players ... more than once. This would create a conflict in the index because a duplicate entry would confuse the player.
If you're handy enough with code, you could likely whip up a script that does all this (and eliminates duplicates), but if not, it's not a simple process to batch rename and weed out the duplicates, which is why the short answer is "no." Sorry!