All “detected” devices can be merged and unmerged later without any issues. The only downside is that you will no longer have individual bubbles, alerts, or device Power Meters for each, tools that might help you increase your certainty about those detections. Just pick one of the three, possibly the one of the three you are most certain of, then use the Merge menu under the Manage tab and subsequent list for that device to select the other two for merging.
Don’t be surprised if more minisplit-related device detections appear over time.
This Sense blog item on AC and mini splits might also interesting to you.