What if you put two passwords for registration?

Question

Information Security

What will two passwords for registration look like from the point of view of information security? Recently I thought about it, I have not seen this on any site yet. The bottom line is that you hash the first password to the second. You write down result in a DB, at an input there is a check by the same hashing? Is it safe? If not, how can the protection be strengthened?

Answer 1

Profit 0 from hashing the first second.
It's easier to hash one.
To enhance protection - you need not to invent, but read more information on the Internet.

Answer 2

The same as one common, equal to the concatenation of these two

Answer 3

Let's start with the intruder model - what threats do you want to prevent with this particular solution?