The quality of your copy will at best equal the quality of your burn. So if your burn was only 60% quality you can more or less count on the copy being the same, as copying errors =errors
This is true for VHS but not for DVDs
Like Maikel Steneker said. You'll get the exact ISO that you made from the original/downloaded. You can also copy a copied disc and get better quality. A bad quality disc has the same data as the iso but not very deeply burnend (I know this is very simplified) but they are still the same zeroes and ones as on the original. If you know copy a copied disc you will still get the original data but you can burn it on a better dvd-r.
IF all the data on the disc is there without errors then yeah you will get the original image, however if your disc had errors burning or is scratched, then your image will contain those errors. It is not possible to get data from a disc if that data didn't burn/can't be read in the first place. Using quality was a bad example, as i can take a shit dvd and reburn with near 100% quality, but the data is still shit, just the burn quality is good.