Yes, there is a seemingly random bug in the OLD DT Register version for Joomla 1.0 where SOME records will not be completed correctly. This is NOT most records... but occasional records. Our 1.0 version has been out of development for over a year now... as to be expected. No one develops extensions for 1.0 anymore.
If you are using the current versions of DT Register, you will not have issues like this.