Stack two tables, one on top of the other. Yes, the first column (A) will be replicated in both tables but that is a small price to pay if your primary goal is to prevent horizontal scrolling.
Think about your user: you may be saving your user from data-overload. This solution may be more user-friendly as you will have to split your data into two logical groups. The user should be able to scan the two tables, and quickly decide which table to focus on.
How you organize and give titles the two tables is crucial for this solution.