Time Machine in 2 diferent HHDs?

[LeandrodaFL]

Lets say I have time machine on "HDD 1". Then I disconnect HDD 1 and connect a new HDD and do a brand new time machine backup, wich I will call "HDD 2". After 1 month using the machine, I disconect HDD 2 and reconect HDD 1. What will happen? Will Time Machine do an entire new backup, or be able to do a 1 month old incremental backup?

 

[Apple_Robert]

It will backup everything within that 1 month time frame it wasn't connected.

 

[MBAir2010]

Lets say I have time machine on "HDD 1"
I have time machine on "HDD 1"

Apple_Robert is correct​

and needs a new avatar!