This　paper　addresses　quaternionic　dual　Gabor　frames　under　the　condition　that　the　products　of　time-frequency　shift　parameters　are　rational　numbers.　For　a　general　overcomplete　quaternionic　Gabor　frame　with　the　product　of　time-frequency　shift　parameters　not　equal　to　12$$　\frac{1}{2}　$$,　we　show　that　its　corresponding　frame　and　translation　operators　do　not　commute,　which　leads　to　its　canonical　dual　frame　not　having　the　Gabor　structure,　but　it　may　have　other　dual　frames　with　Gabor　structure.　We　characterize　when　two　quaternionic　Gabor　Bessel　sequences　form　a　pair　of　dual　frames,　and　present　a　class　of　quaternionic　dual　Gabor　frames.　We　also　characterize　quaternionic　Gabor　Riesz　bases　and　prove　that　their　canonical　dual　frames　have　Gabor　structure.