Deana,
I think your canna is progressing in a typical fashion. The stem with the mature blooms will abort those blooms and typically grow another short stem which produces a separate flush of flowers. We normally will get two to four bloom clusters per stem.
The new side shoot is growing off the underground rhizome and will also produce a flush of blooms. More side shoots will be produced as time progresses this season.
Your new shoot appears to be a bit pale compared to the blooming stem; your plant may need a few more hours of full sun if possible. Unless of course the container has a second rhizome/seed planted.
Cannas are heavy feeders and also need regular nutrient feedings.
Best, Kent
Q