This is strictly from a theoretical standpoint, but,
With both engines running, the front propeller probably gives more thrust, and the proportion will vary with speed, becoming almost equal at high speeds. This is because the rear propeller is operating in the propwash from the front propeller. Calculations give the following at sea level,
Static conditions ( 1375 hp )
front propeller ~ 46300 N thrust ( 62.5% )
rear propeller ~ 27800 N thrust ( 37.5% )
360 mph ( 1375 hp )
front propeller ~ 10020 N ( 50.4% )
rear propeller ~ 9850 N ( 49.6 % )
Greater performance was reported from the rear engine, when the front engine was shut down, as compared to the other way around. To what degree, I don't know.
The above figures are actually doubled as I had set 2 engines for each case. Corrected values are,
static
front ~ 23150 N ( 67.2 % )
rear ~ 11300 N ( 32.8% )
360 mph
front ~ 5010 N ( 50.4% )
rear ~ 4930 N ( 49.6% )