Determinate plant question?

[Talon1189]

Being a newbie to tomatoes the season.....Today I just realized that I mixed up my 2 plants in an EarthTainer. One plant is a Better Boy while the other is a "determinate" plant called Legend. The Better Boy is at 78 inches tall (indeterminate) while the "determinate" Legend is at 58 inches tall Both were planted out 9 weeks ago. I have been pruning the Legend plant while leaving the Better Boy untouched It should of been the other way around eh? The Legend plant has 5-6 blushing tomatoes on the vines today and has some yellowing branches recently and has been putting out for about 2 weeks now. The Better Boy has only put out 2 maters so far but they are tennis ball sized and more bigger ones on the way soon. I have read that determinate plants cough up all the fruit in 2-4 weeks and then the plant just dies Is this always the case with a determinate plant? My plants have been sprayed weekly with Daconil and the Better Boy next to the Legend looks healthy with little or no yellowing leaves or branches Thanks for the advice in advance