Is adding a 2nd sub from a different mfg a good idea, can it be done successfully without sounding unbalanced, or is it better to go with the same mfg?

I currently have a DD15, and thinking about adding a JL Fathom 113 with an SMS-1.

Has anyone done this? Looking for some advice. Thanks.

Sometimes mixing different brands/sizes can lead to a muddiness of bass....

RMK would be a good person to ask this, he has had both JL and Velo in his house at the same time..... He states they are close in SQ and output, but I believe he had the Velo 18..... :)

Good luck