do what pish and CGC said...and always listen to ski for byzantine attribution.
the dirt on the second coin looks like it really want to come off. check that small green spot on the obverse of the second coin, may be bronze disease. it if come off as powedery lite greens stuffwhen scraped with a toothpick or fingernail, it is.
the green stuff on the first coin looks solid and ok, scrape it to compare.