Mixing diesel Oils

[GrayDually]

Getting ready to change the oil & filter on my 2002 F350 Super Duty 7.3L. I have been using Shell Rotella T6 15W- 40 oil for sometime now, but I used to use Amsoil 15W-40 premium heavy duty diesel motor oil. I still have a couple quarts of the AmsOil. Is there a problem if I add a quart of that to the Rotella oil?
Engine takes 15 quarts.