There are only so many poses that are even possible, all of which will have, at some point in time, been used before. Some are more popular than others at a particular time. It's the same with writing, there's only around what, half a dozen or so original stories (or tropes if you'd prefer) in the world - everything else is just a question of variations on a theme. Of course, we still all want to 'feel' original, which is why, when we see things similar to our own, it can create all sorts of feelings (me, I usually get depressed, especially if I see it 'before' I've finished my own piece).
I wonder what kind of pose it is. When it is a unique pose and my ych turned out rather famous, I could see some others get inspired and make something similar too, and I would feel a bit strange but as long as they don´t trace my art, I don´t care. I can´t do anything against it anyway because when they didn´t trace, they didn´t so anything illegal and every going and acting against them is bullying then.
To be honest don't worry about it. More then likely any possible pose has already been drawn 100 000+ times already. While little details might not be the EXACT same, let's face it. There are only SO many poses that any physical body can be put in.
I say indifferent because you can only have so many poses, and you can't copyright a pose in the first place, so of course there will be similar poses, even when it's unintentional. I don't think there's anything to worry about!