Suppose I want to mine the testnet with something like this:
geth --testnet --etherbase '<some address where I keep "real"/mainnet ether>' --mine
What will happen to the existing mainnet ether at that address? Would I be able to split up the mainnet and testnet ether from that address at that point (if so, how)? My main concern is that the different ether will be "mixed" in some way that would essentially render all of the tokens associated with that address worthless on the mainnet (eg. if testnet UTXOs have different metadata that may confuse most wallets when they need to deal with that address now controlling those UTXOs as well as mainnet UTXOs).
New to this (and the ethereum homestead documentation seems to be not up to date as evidenced by the fact that the official docs only mention the Morden testnet rather than the newer Ropsten testnet), so if anything in my verbiage implies any misunderstanding of any concepts, I would appreciate if you would help correct me (eg. what exactly is happening under the surface). Thanks
Note, I've seen this similar post, but the answers there don't seem to really answer the poster's 'what happens' question.