This is indeed a very real concern, as there has been a number of recent messages about members �copying� or �stealing� their presentations and with the extremely large number of worksheets that are now available, the chances of even more duplications is not just remote, it is possible.
The only thing I think I can suggest is that you think of the title of your worksheet and then do a search using your key words to see if anyone has done something similar. For some topics - such as �adjectives� you may have a choice of over 1,000 worksheets. How many you look at is up to you.
But I think the essence of this site is to have contributions that are personal and unique. I know there are a large number of worksheets that are just scanned in pages, or just one simple diagram or picture; but if you have taken time to prepare a worksheet - even though it may be very similar to others - and even though you may have used words or similar illustrations that others in different sheets have used, you should still upload it.
Indeed I am sure that many have seen the contributions of Frenchfrog and Icha and copied their style of presentations - because they look extremely good but I feel also sure that neither of them would begrudge their style being used by others. Is there not a saying that �Imitation is the highest form of flattery�.
The condemnations raised on this site are for those who blatently copy others work without altering it and making it their own. When you think about it also, even though there may be several thousand worksheets, and you create one from your own resources, the chances of there being an exactly identical worksheet is very very small. Unless your worksheet is one or two words with one or two pictures. Remember that out of the millions of pieces of snow that fall, no 2 snowflakes are ever the same. And so I think it will be with original worksheets.
So get your creative juices flowing and compose with impunity. We look forward to seeing your work soon.