Probably you (or the installer) included a Java Memory configuration in the file /opt/alfresco-community/tomcat/bin/setenv.sh (8192M in this sample) but BitRock created a file at /opt/alfresco-community/tomcat/scripts/ctl.sh that is overwriting your configuration to 1024m. This is why two different Xmx and also Xms flags are shown by the ps command.
How to solve the issue
In order to allow standard Java Memory configuration to be applied from setenv.sh file, script generated by installer have to be modified. Edit /opt/alfresco-community/tomcat/scripts/ctl.sh to replace this line...