If both subs were the same then I think the autocalibration would be close, as the 2 subs are different, it may have a hard time setting them. I would be shopping around for an SPL meter, they are not expensive and an indispensible tool for an HT enthusiast.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70