Hi, the size glitch may take place when some of the found items produce incorrect size estimates. Or if there are lost partitions available for recovery, those may be large, and there can be many (though some of them probably corrupted). This is going to be improved in Disk Drill 3, btw.
In your case, you should not recover everything found, instead sort by estimated size, and exclude the files that are obviously not what you were looking for. Most probably, these are a couple found partitions, so you should be able to exclude the whole category of found items, and easily decrease the total recoverable size.