You can Union the tables and then try to make the bar chart that way
If I Union the tables, I will just have a single column of Contract ID. Then I will not be able to get two different bar charts for the two different Contract ID data. Also, I believe for union the fields should be the same for all tables. Date 1 <> Date 2 in this case.
When you union them you'll be able to use the table name field to separate them and the columns only have to have the one field in common to do that.
It seemed like you wanted one table but different bars which is why I suggested it.