Hallo Ryan,
you can not combine two sprites into one sprite without either destroy one sprite and change the animation from the other sprite or destroy both sprites and create an new one with a suitable animation. The other way is to pin two sprites together. Then the two sprites would appear as one. Have both sprites the same texture? If not, depending on the number of possible combinations, the first option would be a lot of work.
Another option, when i think of a wall or a floor with repeating textures, you can create a tiled background and on collision simply add the width/height to one tiled background and destroy the other.