wingchun100
Senior Master
I would just treat them as separate arts, for now. I have a student who has a background in Shotokan Karate. He sometimes does his Shotokan kata as part of his warm-up, instead of the ones I teach. I don't think it does any harm. There may be more of an issue in your case, since they may be more closely connected, but I don't think practicing can do any real harm before you learn the new version.
They are more or less the same moves. However, the Leung Sheung lineage tends to do more "small circle" moves, AKA...smaller moves. LOL