50/50 2x stock/bond can compare to 100% 1x, but if you diversify the bonds then when it comes to rebalance you can pick the more appropriate choice of 'bond' to reduce/add to
For instance if stocks are down and long dated treasury are up, then that can be a better rebalance pairing to rebalance between. Especially if later long dated treasury are down and stocks are up.
Another benefit is liquidity. $50K of 1x, $50K of 2x and need to increase stock exposure by $10K so sell $10K of 1x and buy $10K of 2x. Which enables you to keep 'cash' in the likes of fixed term bonds that more usually pay a higher interest rate.