Welcome to the SuperDuo craziness! There are many sizes and shapes to SuperDuos. They are all pressed glass - so that they are more consistent in size and shape. They all have two holes. They all are somewhat oval in shape. But there the similarities end!
There are now two versions of the tapered SuperDuos that more closely resemble their inspiration, the Twin beads. This version is 2.5mmx5mm. While I've seen some designs incorporate the various versions/sizes of SuperDuos, I recommend that you stay within the colors available in each variety for more uniform designs.