As I understand it, one and only one validator get selected to propose the next block on the beacon chain. This means that the other validator attesting can only attest to one block right? (since there are no other validators selected to propose a block)
So I am thinking, perhaps the attesting process is just to reach a threshold of "validity" before a proposed block gets added?
But I recollect from glancing through the article here https://blog.ethereum.org/2015/08/01/introducing-casper-friendly-ghost/
it has a portion in its description of the consensus where it states:
Eth2 uses Greedy Heaviest Observed Subtree (GHOST) as its fork-choice rule. GHOST selects the head of the chain by choosing the fork which has the most votes (it does this by considering all of the votes for each fork block and their respective child blocks).
I am failing to see how there can be a fork, if only one validator is selected during a slot to propose a block. Anyone care to explain how this works and what I am missing?