He was also the person responsible for UoW's Paul G. Allen School of Computer Science, in total he donated around $50m (with another $10m in match from Microsoft) for the school's foundation.
The library was named for Kenneth S. Allen, Associate Director of Libraries from 1960 to 1982, in recognition of his years of service to the Libraries, and in appreciation of a generous gift from his son, Paul G. Allen, co-founder of Microsoft.
Yes, just like there are two gates halls/buildings named after Bill’s mom and dad. It is fortunate that the CSE building at UW is named after Allen rather than Gates, unlike MIT.
I went to UW in the 90s when Allen library was brand new and the new CS building was just a dream.