YA fiction about 2 sisters (or friends?) in 50's or 60's

I am trying to find the title(s) of a book or series of books I read and enjoyed as a girl. I think it may have been a series of 3-4 books, with 2 sisters (or maybe best friends) named Pam and Debbie? Or Debbie and Tammy? Something like that... The books were mostly just about high school/college life, dating and parties and such. Thanks!

This is a wild guess, but it wouldn't be about twins named Pam and Penny, would it? Those would be Double Date, Double Feature (can't find touchstone, sorry), Showboat Summer, and Double Wedding, by Rosamond du Jardin. They're definitely about high school/college life, dating, and parties.

Yes!! Thank you so much! I've googled everything I could think of and could not find anything!

Hooray!

I adore those books! They were a bit before my time -- I read them as a teen in the early 1980s, when they would already have been 15-20 years old -- but I just love the nostalgic feel of them. The author wrote many other books along the same lines, but those are the four that deal with Pam and Penny.

Rosamond du Jardin has two other series -- Tobey Heydon (sp?) and Marcy Rhodes (?). Another author, Anne Emery, wrote a lot of similar maltshop romance type books.

Double Feature touchstone fairy

^5 Thanks!