How to use grouped/combined register variable output values [values can be repeated/duplicate] of multiple hosts?

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When I list the subnet cidr of every host in an environment I get repeated subent cidrs in the output as multiple hosts can be in same subnet.

What I’m trying to achieve is run a shell command in ansible for each unique subnet cidr from the above output.

Part of the playbook code for understanding purpose

   - name: Generate management cidr
     shell: echo {{ net_addr | ipaddr('net') }}
     register: management_cidr

   - debug:
     var: management_cidr.stdout

   - name: Apply iptables rule for Subnets[management_cidr]
     shell: iptables -A INPUT -p tcp -s {{ management_cidr.stdout }} -m comment --comment "Subnet Access" -m state --state NEW,ESTABLISHED -j ACCEPT

If I use the above playbook code it will apply duplicate iptables rules

And the output of playbook

TASK: [debug ] 
****************************************************************
ok: [wephgyn01.wep.ani.ag.com] => {
    "var": {
        "management_cidr.stdout": "136.26.13.129/26"
    }
}
ok: [wephgyn02.wep.ani.ag.com] => {
    "var": {
        "management_cidr.stdout": "136.26.13.129/26"
    }
}
ok: [wephgyn03.wep.ani.ag.com] => {
    "var": {
        "management_cidr.stdout": "136.26.13.129/26"

. . . [136.26.13.129/26 is repeated] .

ok: [wepr05c001.wep.ani.ag.com] => {
    "var": {
        "management_cidr.stdout": "136.26.13.193/26"
    }
}
ok: [wepr04c018.wep.ani.ag.com] => {
    "var": {
        "management_cidr.stdout": "136.26.13.129/26"
    }
}
ok: [wepr05c002.wep.ani.ag.com] => {
    "var": {
        "management_cidr.stdout": "136.26.13.193/26"
    }
}

. . . [136.26.13.193/26 is repeated] .

ok: [wepr03c005.wep.ani.ag.com] => {
    "var": {
        "management_cidr.stdout": "136.26.13.65/26"
    }
}
ok: [wepr03c008.wep.ani.ag.com] => {
    "var": {
       "management_cidr.stdout": "136.26.13.65/26"
   }
}
ok: [wepr03c004.wep.ani.ag.com] => {
    "var": {
        "management_cidr.stdout": "136.26.13.65/26"
    }
}

. . . [136.26.13.65/26 is repeated]

So what I thought was to store register variable output into a list and make the list unique in Ansible and then use the list with the command.

Tried multiple sources but couldn’t find anything useful. Any ideas?