It's only possible with RBF transactions, and if a node is aware about the most recent transaction, it will reject any previous transaction. But still these older transaction aren't 100% invalid, a miner can happen to mine an older transaction if they aren't yet aware about the new RBF transaction.
But without RBF the earliest transaction will be kept by nodes, and transactions that attempt to spend the same coin will be rejected. But until the spending is confirmed, any of those transactions can be included in a block. Broadcasting transactions isn't the only way to reach miners, you can theoretically contact miners directly, give them raw transaction and ask to include it in a block.
So, invalid in terms of being able to included in block and being able to be propagated by nodes can be slightly different things.