It depends on your scanner and the paper surface and how flat you can get the paper, but I find it difficult to get a scan that I'm really satisfied with from a print unless the print is dry mounted, and I usually don't dry mount. If the paper isn't perfectly flat, you get distortions and unevenness, and if you scan in color to reproduce the tone of the print accurately, sometimes one gets blotchy color when the print isn't flat. Some paper surfaces don't scan well and make the print appear grainy.
Some people seem to have more success at this, perhaps because they dry mount or use paper that sits flatter or that has a surface that isn't as difficult to scan.
If I must have a digital representation of the print, I usually find it easier to dupe it on a copy stand with a digital camera using standard copy techniques.