As Vlad pointed out - the A.I uses various gun parts, and art assets to generate weapons with randomly generated stat values. The base brand and type of gun speciality is one common element - it's through that common element you'll get "shared" names such as Ripper. However, it'll have something before it - like QDD4 Ripper, or XTOD Ripper - obviously, the A.I is randomly generating the 4 numbers before it, while the developers have kept the core design of the gun as the "Ripper" type under "so and so" brand (i.e, Dahl, Tediore etc.)