Of course, there is no limit to the number of banner ads. You are free to choose how many different banners you would like to display, and you can use these in various locations. Here are some benefits of running multiple banners at the same time:
Wide range of target groups: With ads running in different regions or countries, you can reach a wider audience.
A/B testing: You can experiment with different designs and messages to find out which is the most efficient.
Maximized visibility: The more places your ads appear, the greater the chances of generating visitors with them.