That is the thing with polymer clay - nearly everything has been done before, but if we let that stop us, well none of us would make anything!
For the first 2 or 3 years that I was claying in earnest, I genuinely thought I had invented millefiori caning! I was quite pouty when I saw someone at a craft fair who had made beads using the same ideas. Then I find out people were even doing it in the 60s before I was born.
I mean, that is pretty low isnt it. To copy someone before they have even been born. Some people have no shame!
But I think it is really common in crafts - that whole serendipity thing. Good ideas bubble up in multiple places around the same sort of time. And we all use the medium in broadly similar ways so we think along broadly similar lines when it comes to "I wonder if that will work..." or "hey, I wonder if this craft technique from glass/ceramic/sugarpaste etc will work in clay?" and so consequently lots of us end up doing often quite similar things
When the mica based metallic clays first came out - there were two pretty well know clay artists at the time who both independantly stumbled across the mica shift properties of the clay and each of them developed their own ways for manipulating that. Now the concept of mica shift is pretty universal but at the time it was very new and exciting for us clayers!
Emma