CatyO, pregnyl is hcg whereas the pessaries are progesterone. I've found that 3 pregnyl shots works great as a substitute for progesterone in a stim cycle (which is when I need the most luteal support). If your pessaries are still in date, there should be no harm in you using them, but you really should run it past your FS first (making clear that you already have them, not that you're asking for more). That said, the first time I was told to use only pregnyl and no pessaries I did use with some left over pessaries I had at home because I was nervous about it...