Actress Peggy McCay as Andy's Old flame "Sharon DeSpain" in Episode #82 "Class Reunion"

Actress Betty Lynn as Barney's love interest "Thelma Lou"

There are often discussions here at iMayberry.com along the lines of:

"On the class reunion episode, did Betty Lynn play andy's old high school sweetheart?"

Well, as you can see above, they are not the same person. You'll have to judge for yourself as to how much they actually look alike. For me, they have similar eyes but that's about where the similarities end. Their noses are different as are their smiles. I will grant that they could, at least looking at these photos, be sisters or related.  I'll leave it to you to make your own conclusions.