Neither doubles the load.
SRT magnifies the load, can optimized the loading, and can have back-up crotches.
DdRT means you have to have no snags in your standing-end in order to descend in an emergency.
Rarely do I go higher than my 120' main climbing line allows me to get down from lickety split, in an emergency, with a choked climb line. If redirected with a base tie, I tire two ropes together.
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I don't know how many climbers carry their ropes. Carrying your rope mitigates the DdRT trail from locking up in a stub/ crotch/ branch or being caught in brush in the ground.
Eventually, you will cut your rope or come off the end of your DdRT, same as you will cut your SRT-down strand to base tie, and kill people on the ground by dropping stuff in them.
Or you won't through safe work practices, including a full-life-support, secondary tie-in while cutting.