EDIT:
Oooops, it must have taken me ages to compile my message, since a ton of activity has evaded my attention…
I’m just a nother user and can’t offer a definitive solution for your problem, but…
As I haven’t ever seen something like your problem in my library, I’m sure Roon doesn’t split albums between different DR readings - if it really did, this would cause s…tstorms about it on this forum!
It is worth noting also, that not all tracks of an album necessarily have the same DR.
That said, you are seeing DR readings computed for a set of 8 or 10 tracks, as in your example, compared to DR readings for a single track, respectively.
I know that for sure, since I have recently setup a Raspberry Pi, running official EBU128 DR metering software while streaming to my RAAT endpoints, so I can verify individual track DR and accumulated album DR.
My guess is, that it’s most likely caused by inconsistent tags, embedded into the individual tracks.
Maybe have a look at them in Roon and an external editor for reassurance and report back.
Good luck in fixing this annoying glitch…