I’m glad that helped. The reason why it helped is because both avatar plugins you are using are filtering the same WordPress hook with the same priority (level 10). My plugin allows altering the execution priority. Setting it to lower value (9) will cause my plugin filter to execute before the other plugin with filter value 10. Before changing it to 9 both plugins were set to 10 and it just happened that my plugin was being executed after your Avatar Manager plugin. Now after lowering the filter priority, Avatar Manager gets executed after my plugin, so its avatars are not overriden.
If you ever experience any compatiblity issues with other avatar plugins, try tweaking this filter priority value. It allows you to control the execution order of WordPress filters.
Cheers,
Daniel