For unregistered solo mines, once they get one orphan, blockchain starts tagging them falsely as double spenders. It's a silly false positive that seems to never go away.
I have an address tagged like that. It happened doing p2p mining. I found it so annoying that I no longer mine in p2p pools.
This is the address.
https://blockchain.info/address/1Fo2K52Rz7LZw9fcF5BDdDBjfNaViQ8J3xand as far as I understand I can't get that tag removed.
That happens every time a p2pool block is orphaned. It's nothing more than a false positive because the generation transaction actually happens, but is overwritten when the longer blockchain replaces the one where p2pool found the block.
but the tag lingers with the btc address. this is bad for my accounting as i like to use the same address . i have had more then one person ask me why i have the address marked with the warning. so i opened new addresses. which in turn makes my tax accounting harder.
i do a tax return with my btc income included. so i will need more addresses due to this issue.