If its converted, does that mean there is 2 dero chains then, rather than the single. SO in essence, 2 Dero coins ?
No, it means the old PoW algo will stop working. The coins from the old chain can be converted to the new chain, but once the algo changes no new blocks will be added to the old chain.
In other words, existing mining software and ASICs will stop working.
My understanding - though this has not been confirmed or denied by the DERO team - is that only the wallet daemon will be usable to mine on the new algo at first.