As a general rule, -R disks are no less compatible than +R. In fact, many older machines prefer -R unless the +R disks have been bitset to look like a DVDRom.
What type of dvd burner do you have in your computer? It may or may not have the ability to bitset +R disks and have them appear to be commercially made DVDRom disks.
One way to copy them is to make an ISO file of the entire disk, then burn the ISO file to a new one. You can use a free burning program called ImgBurn for this. www.imgburn.com When you start the program, click on Create image file from disc to start the process of making the ISO file. Once it is on the hard drive, restart ImgBurn and click on Write image file to disc, select the newly made ISO and burn at a moderate speed to your new disk. I suggest 8x or 12x speed when using 16x blank media.
If your burner can bitset, ImgBurn can manage this also. Look under Tools-->Drive-->Change Book Type (another term for bitsetting). Find the make of your drive and click on the tab for it. Under Change For: select DVD +R media. Under New Setting: select DVD-Rom Now click on OK.
Use good quality blank disks. We normally recommend Verbatim, but they are in the process of changing their suppliers. If you can find the older style Verbatim with AZO on the packaging, these would be the best to purchase. Sony disks are a reasonably good substitute if you cannot find the Verbatim with AZO dye.