Been rather busy (and out of the office today and tomorrow) so haven't been able to respond to questions - will only do a few this evening (I do have a life now and again too!). Please note (from your other posts) that if you have urgent questions, you should go to customer support, because we track service level targets there, rather than the forums which are an open forum for anyone (Cadence or the community) to contribute.
I assume that "PDF" means something like "Probably Density Function"?.
Anyway, did you try searching for the word "seed" in the VerilogA reference manual? <MMSIMinstDir>/doc/veriaref/veriaref.pdf - it's fairly clearly described there. Seeds are used by random number generators to initialize the sequence of random numbers - for the same seed, the sequence will be the same - but changing the seed will give a difference sequence. In general you want repeatability from simulations so keeping the same seed is often wise (the same is true for Monte Carlo, for exactly the same reason).
The distribution (mean/sigma) will the the same (within accuracy limits for the number of points chosen), but the precise sequence of numbers will vary dependent upon the seed. That's all.