SPSS Statistics provides both the Mersenne Twister and, for compatibility, an older shift-congruential generator. By default, the older generator is used. Use
SET RNG=MT or the Transform>Random Number Generators menu item to change this. The
MT should give you all the numbers you need.
There is also a user-contributed Python function that fetches truly random, not pseudo random numbers generated from atmospheric noise. These are fetched from a website that has some rules about quantities that you should read. The package is
tr_rnd0.1.zip. It can be downloaded from the SPSS Community website in the Python Modules collection. Of course, this requires you to use Python programmability. The tools for that can also be downloaded from the Community site.