welcome to the Icinga community.
I am not quite sure if I understand this correctly. Your switch duplicates the ping packet?
As far as my networking understanding goes duplicated ping packets should never occur and are rarely (if ever) a good sign. I suggest to investigate this.
You can acknowledge the warning/critical state in Icinga Web 2 in the problem handling section for each host/service.
This will not change the state but it will tell others that this problem is under “investigation”.