That is a pseudorandom number generator.
So, yes, that's what all PRNGs do:
Given a specific seed, always produce the same sequence of only seemingly random numbers. That happens by initializing the internal state from the seed, and then, every time a number is generated, updating the internal state and outputting a number.
I've only superficially looked at MWC1616:
The two generators have the form
x(n)=a*x(n-1)+carry mod 2^16 and
y(n)=b*y(n-1)+carry mod 2^16,
in this case
b are choosen as 18000 and 30903
Considering that it's mostly a linear algorithm, I'd say it should perform especially bad in terms of being able to conceal the internal state from reverse engineering.
I'd expect that algorithm to be bad in terms of quality, too. This can even hypothetically only achieve a sequence length of 2³² (so, easy to simply brute force the next number by going through all 4 billion in minutes at most values on a modern PC) albeit having 64 bits of state, but I'd be surprised if the sequence length was not actually shorter.
All in all, a very bad algorithm. What ancient library / programming language brought you this? If possible, consider using a different random generator (from different authors, tbh; "roll your own PRNG" is about as clever as "roll your own crypto") or different platform.