The on chain voting features coming with the Voltaire rollout will allow users to use those voting systems for other things because they are part of the base protocol. So incorporating voting on chain with a plutus contract will be possible.
just not right now.
Looks like it does not at this time. If you use Yoroi and move the rewards over from the reward key to the main wallet that is one work around. The other would be to have a tx on Daedalus as that seems to consolidate from the staking key as well to the main wallet.
However, I'm not sure about future versions of catalyst which could change how this functions ...
You either have to vote with your first account, than reinstall the app (or just wipe its storage) and vote again with your second account.
Alternatively you can use any application cloning app on iOS that will allow you to setup the same application with two acocunts.
You can already vote using the Catalyst mobile app if you have ADA in a wallet you control.
That said, it's still in a kind of beta phase that depends on the Ideascale platform.
In the end, there will probably be a voting section inside the Daedalus and Yoroi wallets and we will no longer need Ideascale for the voting process.
It is unknown yet how long it ...