I am wondering if copying a dual layer DVD to two single layer DVDs is a more "reliable" way to go? I have found that DL DVD blanks are not the most "robust" (I have had a failure rate of several %). I guess the real question is: are single layer DVD blanks more resistant to scratches and are they more fool-proof to burn? There would be a small cost advantage which would be offset by spending more time to copy (deciding the split location; two copies, albeit quicker ones, etc). But if the resulting copy is more reliable and robust, then it may be worth the effort.
Insofar as there won't be a layer break position to worry about (which is an area where burn errors are prone to occur), then yes. That said, I've never experienced a problem doing the following (this is my primary method of backing up my collection--and I happen to burn faster than what I'm suggesting in the link): http://forum.slysoft.com/showthread.php?t=327
