Think you´ve got a point here. Although either is digitally restored the sound of Garcia-Rojas with it´s reduced mids is much more transparent, whereas the diSarli-Podesta version still preserves a hint of shellac-charm. I like "Junto a corazon" especially for that pasodoble-like cadencia (with triplet). In diSarli´s version the cadencia is at the end ( 3:03 ) with a slight ritardando, whereas Garcia put it in the middle ( 1:36 ). Either dancers also emphasize this cadencia. You can find it near the end of the second photo of Jantango´s blog entry.
Garcia released "Junto a tu corazon" july 1942, whereas diSarli´s version already was put on the marked in june. Don´t know if they had tried out their interpretations before, so they could eventually knew of each other. I also don´t know if Stamponi (the composer) played it in the public himself. According to todotango Stamponi that days was part of Calo´s line-up before he changed to Orquesta Radio Antonio.
I also found a third and rather new version by Armando Cupo with Alberto Morán singing which I don´t like that much.