Photos is duplicating (jpeg & heic)

I asked about this at the Apple Store Genius Bar & was shown to uncheck the HEIC option to keep it from continuing to happen,

Your Mac with High Sierra 10.13.6 can handle HEIC perfectly and you should be able to use the space saving HEIC format on your Mac without creating duplicate JPEGs in your Photos Library. Where are you seeing the duplicates? In your Photos Library or in some caches?

The most common reason for HEIC photos being duplicated as JPEGS is mixing two import methods - if you transfer your photos automatically by My Photo Stream, the HEIC photos will be transferred as a JPEG, because My Photo Stream does not support HEIC. If you then import photos in any other way from your iPhone, by iCloud shot Library or by connecting the device to USB, the original HEIC versions will be seen as new photos and imported as well. If you want to keep your photos and videos in the new, space saving format, do not disable HEIC but My Photo Stream and import only by iCloud Photo Library or only by using a USB connection but do not mix import methods.

To remove the HEIC duplicates you already imported you can search for them with a smart album:

• To create the smart album use "File > New Smart Album"
• Set the rule to "Filename includes .heic"

Then you can select all remaining heirs in the smart album at once and delete them with the key combination ⌘⌫