Could you post more details about the documentation that suggests that the fuzzy printing was intentional? Was someone just hypothesizing at a theory, or is there contemporaneous evidence of the reasoning?
If intentional, you'd think that virtually every Roosevelt album would have the same fuzzy printing on the "1876" stamps (both the 5c and 10c), but as you indicated, they do not. Most are normal.
To me, it looks like a kiss impression (Siegel once described it as a "bounce print") printing anomaly, a type of EFO variety which I have never seen the catalogs list.
For the record, the blurred printing anomaly can also be found on the 10c, again rarely.

(Siegel sale 984 lot 44)