IDE is not able to multi-task two drives on the same channel - which is one reason why SATA has one drive per channel.
If an operation is outstanding on one drive, then the other drive on the channel is unavailable until the operation on the first drive has completed. This can mean that disc to disc copying won't work if both the source drive and the writer are on the same channel - but it may work just fine. It can be a case of experimenting.
A hard disk and a writer on the same channel may cause problems - but it may work fine for you.
If possible, it's best to put optical drives on your motherboard IDE channels rather than a controller card. You may also find that optical drives work better with the Microsoft IDE drivers than IDE drivers from the chipset or motherboard manufacturer.
There's no requirement to have a writer as a master - this Dell Precision 650 came from the factory with a CD-RW as a secondary slave, and my ND-2500A is now the secondary slave.