Do I get additional tax benefits if I contribute to multiple ABLE accounts?

No, tax benefits for ABLE accounts and 529 plan accounts are aggregated for tax purposes by contributor, not by ABLE account or 529 plan. Anyone who contributes to one or more ABLE accounts or 529 plans with beneficiaries under the age of 21 can receive tax benefits up to the maximum allowable amount for that tax year and the state you live in.