Most built-in random number generators are "cheap" Linear Congruential Generators:
Xn+1 = (a Xn + c) Mod m
They produce a fixed output sequence. The sequence is started at a point determined by the seed. The seed is similar to saying "start the sequence at index n". Re-seeding the generator starts it at the SAME point.
Will produce 50 reasonable random numbers. Running the whole batch again will produce the SAME sequence, because the seed is the same.
will produce the SAME value 50 times because the generator was re-seeded (set back to the same initial index on every run).
The correct usage is seed ONCE, use MANY times.
However beware, when used in a select, it is only evaluated once, eg
will output the SAME value.
-- Seed ONCE (based on the current millisecond)
-- Use MANY
will produce 50 reasonable random numbers, and every run of the whole batch will be different.
Ultimately, it is the quality of the INITIAL seed that governs the output sequence. There are numerous strategies for a good seed: current date, GUID, CHECKSUM etc. Develop one that works for your situation, but remember: SAME seed = SAME sequence.