Groups listing in duplicate

On my site, I have found that at times groups get listed in twice. I am adding a screenshot for that. They appear twice or thrice in group directory and also in the sidebar group widget. It doesn't happen always but it does happen many times.

Also I have cheked that underlying there is only one group as the same activity reflect in all such groups and you delete one and all two-three listings disappear.

I need help to sort this.