Merge Hash with appending the values in same key

hash1={"key1"=>"value1","key2"=>"value2","key3"=>"value3"}
hash2={"key4"=>"value4","key1"=>"value5","key2"=>"value6"}
hash1.merge(hash2){|key,oldval,newval| [*oldval].to_a + [*newval].to_a }