Do you mean you have 2 users than can approve without waiting for any order?
You can use branched execution in a sub process like this:
Remember branched execution will execute separately, so in order to make sure both branches have been finished, you need to contain it into a sub process.
Then call the sub process inside main process like this:
I use the Terminate End Node in the approval sub process to drop the process if one of approver reject.
So after rejection, process will disappeared from all user taskbox.
If that was the case, there's no need for BothApproved conditional node on main process.