This is a convoluted question, so bear with me :)

Please keep in mind I'm using "I" so as to keep this question simple -- it's technically a hypothetical....

I work freelance for Employer X, but work 5 days a week. I was promised 2 weeks vacation when I was hired. I don't get paid enough to support myself, so I was forced to pick up a second job. My second job occasionally requires me to work a Friday or a Monday. Employer X told me that its OK if I take the occasional Monday or Friday to work for the second job, since Employer X can't pay me enough to work only for them.

After I've been working for Employer X for months and have been taking that occasional Monday and Friday to work the second job, Employer X turns around and says "Oh yeah, and those days you've been taking off to work your second job were actually vacation days so you no longer have the vacation you were promised."

IS THIS LEGAL IN PA??

Thank you VERY much :)

I don't normally answer "hypotheticals", but unless you had a written agreement to take that time off without pay and without your vacation being charged, yes it is legal. In addition, "freelance" normally indicates Independent Contractor status, not employee status.