Does it mean that hyphen.cfg loads the two files consecutively? Looking at \proc...@language in hyphen.cfg, it appears so. Should probably look at the doc instead of the code, though :).
In any case, whatever babel is doing, would it be possible to have hyph-utf8 generate one file, say loadhyph-sr.tex, which reads both -latn and -cyrl? Putting two files on a line in language.dat is unprecedented and would need numerous changes throughout the infrastructure.
