We numerically investigate the effect of Gaussian barrier height and width on gray soliton ensembles for symmetric and asymmetric potential traps. Gray solitons are created in double-well potentials by density engineering techniques. Two identical Bose-Einstein condensation fragments are confined and made to collide by turning off the Gaussian barrier of the double-well potential. We found that the number of gray solitons can be manipulated by the height and width of the Gaussian barrier. We also investigate the population dependence of gray solitons on coupling strength. In addition, we also study the effects of asymmetries present in the double-well potential. Such asymmetries are always observed to perturb the collision points of gray solitons. Stationary dark solitons are then created by a phase imprinting method, and the initial asymmetry of the double-well potential trap is observed to oscillate the dark solitons.