IP Conflict in Server and F5 load Balancer

Can I assume you're trying to use the same IP address on the F5 that you're using for the Linux server? And are you configuring the F5 to load balance services on the Linux server? If yes to the first, it's generally not meant to work that way when load balancing end point services like web servers. In this case the F5 presents a virtual representation of an application to users with a single dedicated IP address. Users contact that IP address for services and the F5 load balances those requests to potentially many servers on different IP addresses. The F5 would not use the same IP address assigned to another server.