Can a processing box have more than one algorithm? If not, can there be multiple processing boxes in a row?
You can include more than one process in a process box, but it is important that your flowchart is clear and easy to understand. If including multiple processes in one box makes it look busy or confusing, it is better to opt to one per box. When you do put more than one in a box, make sure they are separated by a new line of text.
A sequence of process boxes is not an issue.