Convert ten individual .cdr files to one 10-page .cdr file

If you are going to do this often, it may be worth writing a macro.

If it is a one-off requirement -- do you actually need the CDR file, or are you only doing it to be able to print all the files together? If you are, then you don't actually need to create the CDR file. You can just open the 20 files at the same time and in the print or publish screen select the print range as "documents" rather than just "current document".

There is one major reservations here. You cannot change the order of the documents once opened, so you must open the files in the correct order. In practice this probably means opening the files one at a time -- because if you try multiple selection in windows explorer and drag the files into CorelDraw, the first and last files tend to come in first.

If you do need to create a single CDR file -- then one possibility is to open the 20 files using the above procedure, publish to PDF and then try importing the PDF into a new file. I don't particularly recommend this, because you are then doing conversions and hence may be approximating some of the features. But I'm not aware of a better way (without writing a macro) and it may possibly get the job done well enough to satisfy the requirement.