Building a house, getting taxed twice

Please help me make sense of this… I’m building a house, using a home builder. The builder has provided us all of the subcontractor quotes which include tax and the builder’s markup. When we received our package price from the builder, it includes an additional tax on the total. The quoted items already included $58k in tax. The final contract price carries an additional $62k - $120k total tax burden. How does that work? I’m in Washington.