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Is the first wallet empty?
Are the Bitcoins now in the second wallet?
Did it "cost" anything to a third party?
Addresses: Contain your bitcoins (controlled by it's privatekey).
Wallets: Contain your addresses.
If you have an address with bitcoins controlled by privatekey ("PK1") in one wallet ("W1"),
and then you create a second wallet ("W2") and sweep your first address ("PK1"),
your second wallet will transfer your PK1 coins and place them into a new address ("PK2")
within your new wallet ("W2").
After this happens, W1 no longer have the bitcoins in PK1, they are now in W2's PK2.
It does not cost anything other than the miner's fee to sweep those coins. Depending
on the mempool at that time, could be cheap or costly.
Depending on the circumstances, it may be better to IMPORT your PK1, into your W2, if you
do not wish to pay a miners fee to sweep. But it is always recommend to transfer coins to new
addresses since using the same privatekey on multiple wallets whether online or software increases
chances of compromising it (since your privatekey is in more than one location).