Hi @anhdungle
Sorry for a late reply lol 
Alpenglow considers that many different blocks in one slot might be proposed by a malicious validator. Alpenglow introduces this notion of a ‘skip’ vote and in most scenarios such a slot would be simply omitted. In some scenarios if many nodes see one of the blocks first it could also be voted on and finalized eventually. Point is, Alpenglow considers all these possiblities and guarantees that we’ll skip the slot or agree on exactly one block.