So in case node 1 gets offer 1 and then offer 2 with identical timestamps and node 2 the other way round, how is this resolved? Do they ask a third node?
The way the Ripple consensus works, when the ledger is closed ALL nodes have come to an agreement on an identical set of transactions which will be applied. The timestamp on the transaction doesn't matter, only that they are both in the same set of transactions applied to the current ledger.
What you mean to ask is "what happens when two identical offers from different people are in the consensus set of transactions?" I don't exactly how Ripple does it, but there has to be some unique characteristic which can order the transactions in a way that cannot be manipulated. Sorting them by their hash would be one obvious way.