Help! - NPC Boss for tomorrows game just changed into a Dragon!

Hi  I have been updating the NPC in question on the new 5E sheet to include his spells in the new spell section. When I went into the NPC edit box to add his spellcaster level all of the stats changed to those of an Adult Green Dragon! Can anyone help? is this a known bug and is there anyway to revert to the original stats? This was a unique NPC I created so if not I am going to have to start again, so any help appreciated. Many thanks :)
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Could it be you were dragging something to the sheet and the search results changed and you didn't notice? This is a known issue that has yet to be fixed. I get this happening all the time and instead of the thing I wanted to drag, it is a monster. https://app.roll20.net/forum/post/4956028/slug%7D#post-5166485
Thanks for the help Doug. i guess this could have happened while I was populating the spells.  Is there any way to undo this?