Many uncoloured maps are much more attractive with skillfully applied modern colour. A few collectors prefer maps only as originally issued coloured or not but most dealers agree that skillful modern colour enhances interest and thus value of many maps. It is very much an individual collectors choice. Very few maps have been deliberately faked to deceive but some have been reproduced and occasionally they are confused with the original. There are some obvious signs that they are reproductions.
Reproductions are usually larger or smaller than the original.
If you can determine the size of the original map comparisons are easily made. Folds and plate marks. Older maps were often produced by a copper plate and then folded at least once into a volume. These marks are obvious on the original and usually still physically present. On a reproduction they can often be seen but they are flat photographic images.