If you have 1 in-tank and one in-line and the inline is more powerful then the one in the tank, will it burn the one in the tank out?
Probably, cause the bigger one is trying to pull fuel that the smaller one isn’t pushing out.
That’s prrobably the reason for using a surge or swirl tank. It is a separate area for the second pump to pull from. The in tank pump will feed the swirl tank. No worry about sloshing this way either.
Like mns13 said a surge tank is a good idea.