50/50 chance they will work. Mixing brands of memory, even with same spec's, is a hit or miss. Not just Dell's, I have a home built desktop (for my recording studio) using an ASUS motherboard. I have 16GB of Corsair memory and 16GB of GSkill memory (same specs). Either the Corsair or GSkill will work OK but with both installed it will not boot.
Give it a try and if works you lucked out. If not, it will require all the same brand/type memory.
BTW, the Workstation section of the forum is the correct forum section for Precisions.