A lot of makers sell flutes that they describe as “Rudall” or “Pratten”, but many are really not very close to the originals. I am in the early stages of making flutes myself, and have studied (and accurately profiled) a lot of antique flutes and flutes from modern makers, in order to gain a better understanding of design parameters and effects. I have noticed that some modern makers’ Pratten flutes are almost identical, acoustically, to other makers’ Rudall flutes. The similarities can be so close that one could imagine they even used the same reamer (or made their reamers based on the same flute). When I say “acoustically”, I am referring to their bore parameters, embouchure cuts, tone hole size etc.
In practice, I think modern makers tend to refine their designs iteratively, trying to approach what they perceive to be the best Irish flute for modern sessions at a=440 hz – which, by the way, is a very different target than the original makers of antique flutes were aiming for. So, its really not very surprising that modern designs tend to converge on a fairly similar point in the design space.
I think it is also worth noting that there really never was a single “Rudall” flute design. There are original “Rudall” flutes that occupy many very different points in the design space, with respect to bore size, profile, tone hole size etc. Large bore, large hole Rudalls are quite close to Boosey Prattens, but older, small bore, small hole, Rudalls can be very different.
Nowadays, when ITM players talk about Rudall vs Pratten flutes, often (but not always) what they are really referring to is simply whether the flute has a single body section or a separate left and right hand section. This is acoustically insignificant (unless back-reaming is employed at the joint - which some original Rudalls have).
Somehow, Rudall and Pratten have become two accepted marketing terms, used to describe Irish flutes, but like all good marketing terms, they don’t really have a lot of meaning anymore (in my opinion). 
