If you've been invited to a party by a friend who hasn't first cleared the invite with the host, it could be cause for an awkward situation.
A good rule to remember: Double-check that the invitation is 100 percent definite. After all, it is the host who knows how many chairs there will be at the table and how much food is available.
In order to avoid misunderstanding, say thank you for the invitation extended by the party's guest and then check in first with the party's host.