We performed dynamic Monte Carlo simulations of half-half binary blends of symmetric (double and mutual) crystallizable polymers. We separately enhanced the driving forces for polymer-uniform and polymer staggered crystals. Under parallel enhancements, polymer-uniform crystals exhibit faster nucleation and growth, with more chain folding and less lamellar thickening, than those in polymer-staggered crystals. We attributed the results to intramolecular crystal nucleation, ruined by enhanced polymer-staggered crystallization. Our observations provide direct molecular-level evidence to support the fact that intramolecular crystal nucleation is favored by polymer crystallization in quiescent solutions and melt, which yields chain folding for the characteristic beta-sheet or lamellar morphology of macromolecular crystals.