does social securty penalize you if you have another retirement plan?

I am a government worker, and I will eventually have a 20 year military reserve retirement plan set, another Gov retirement paln, and social security since I’ve been paying into from 1987 to the present? A friend of mine informed me that since I will drawing other retirements, SS will give me a lower amount when I retire is this true?

Yes! It is called Windfall Elimination Provision. See SSA Publication No. 05-10045.