When HCMC ask for financial proof that you have already submitted, I think it's because they want to see a very recent bank statement that shows the money is still there. I was involved with an application there and they asked for the same thing. A statement with today's date on it will show them that you didn't just borrow the money for a day then give it back.
When embassies/consulates ask for things you have already submitted I think it's because they either want more detail, some clarification, or a more up to date version of what you've given them. I do not think they just want the same document again.
Contract should, as mentioned above, state you're able to work remotely. In a recent application via London, further information was requested; they asked for work contract even though it had already been submitted. I saw that as a request for clarification of the remote work status/permission, and a further letter from the person's line manager as a specific response to the embassy, dated the day after the request for more information, explaining that not only was the person able to work remotely as stated in their contract, but they had permission from the company to work in Thailand. Also mentioned was that the company has no Thai clients, and derives no income from Thailand.
Application was successful after submission of the extra documentation.
The requests seem to have a generic style so I see that if they're asking for something you've already submitted, they want more detail.