Title says it all Putting a new latch on the coop door, trying to decide if a latch like this with a carabiner instead of an actual padlock will be secure enough.
They will probably be able to open a carabiner, if you use the same lock with the type of snap used like on horse leadlines,they should not be able to open it.
The second lock shouldn't be used, they will eventually be able to figure it out.