Questions about wormhole ETH contracts

[Lbqds]

Hello,

I'm learning the Wormhole bridge protocol recently, Wormhole bridge is awesome, and thank you guys for your great work!!!

But I have some questions about Wormhole Ethereum contracts, from the Etherscan I found that there are two transactions called the Wormhole bridge implementation contract directly:

Tx1 and Tx2, these two transactions both call submitContractUpgrade​, the purpose of these two transactions seems to be to modify the storage of the implementation contract, can someone explain why these transactions needed and what storage modified?

And, before these two transactions, there is a transaction Tx0 which set the guardian as the null address, so it looks weird that both Tx1 and Tx2 succeed, it should be failed because we can't have valid signatures from the null address, or am I misunderstanding something?

Thanks very much for your help.

[Lbqds]

I know why these transactions are needed, please ignore this discussion, thanks.