Garfish is refering to the Serial Copy Management System (SCMS) that just about all consumer digital audio products are required by law to support.
There is a flag in the digital header for the music data (on CD, DAT, etc) that is set by the originator of the music to enable SCMS. There is a second flag that indicates whether this data stream is original or consumer copied. It is not set on the original (CD) source.
An SCMS equiped copier looks at the first flag to see if SCMS is enabled for the current datastream. If so, it checks the second flag.
If this second flag is clear the copier will allow duplication. It also sets this flag (as well as the first flag)in the copy it produces. If the second flag is set, the copier will not allow duplication.
So if your source is direct digital dub from CD, the source has the first flag (SCMS enable)set, the copy has both flags set, and you will be unable to duplicate the copy on consumer grade gear. However, if the source is analog through the recorder's A/D converter, the first flag (SCMS enable) should not be set, and you should be able to duplicate the copy (and all generations of duplicates of the source).
Since Sdcampdell's CD was made from an analog dub, it should not be SCMS enabled and this should not be the cause of the problem. BTW, many duplicators give an indication if SCMS prvents copying.
Does the duplicator refuse to copy the disc up front, or does it quit after attempting to process the disc? If the latter, then perhaps your Memorex CD-R blanks produce copies with too many errors to successfully duplicate.
Such a disc would play ok since the CD player's error correction and concealment systems would handle most problems. To gain speed, the duplication process bypasses elaborate error correction.
I can't think of anything Memorex could do to intentionally copy protect the blanks.
Stick with the brands that work for you.