When downloading a preset which was created using "PASTE COPIED JSON" option and then trying to import it to BTT, BTT will insist to overwrite the primary preset with the newly imported preset.
I guess this is because pasted JSON does not include the BTTPresetName property.
Expected behavior: Suggest a new preset name when importing preset without a name.
BTT will only do that if a trigger with the same UUID already exists in your current setup to prevent conflicts. This means this will only happen on your system, but not for other people who download your preset.
BTT recognizes old versions of presets by doing this and replaces them with new ones.