Can there be more than one instance of a servlet at one time ?

Avi Kak

The answer to this question is on page 20 of the Java Servlet API Specification Version 2.2:

It is important to note that there can be more than one instance of a given Servlet class in the servlet container. For example, this can occur where there was more than one servlet definition that utilized a specific servlet class with different initialization parameters. This can also occur when a servlet implements the SingleThreadModel interface and the container creates a pool of servlet instances to use.