I don't think it has been reblued; but the police may well have rebarreled it. (Or it may have been transferred back to the army and they may have rebarreled it). It does have halos around the X's on the frontstrap, lending credence to the transfer theory.
It could also have been arsenal refinished at some time. Might even be a Russian capture/VOPO refurb. The fonts on the barrel look like original German mfg's stamps, not aftermarket markings.
I don't believe that an arsenal refinish or even a VOPO refurb lowers any value a Luger/P38 might have. I look for pitting. I don't see any real pitting on this Luger, just normal decades-of-use wear. Having a replacement barrel doesn't bother me either. Lots of Lugers were rebuilt by the Army or the designated repair depots. they could have replaced all kinds of parts.
I wouldn't say it was a collectible; nor would I say it is a beater. It's just a nice all-around Luger at what is right now a reasonable price (to my way of thinking) = $820 with 11 hours to go...
I wouldn't go any higher...but this is all just one dummie's $.02 worth...