I have a MacBook Pro with only TB3 / USB-C inputs, and I'm experiencing a lot of double-hits with my drum pads when using a USB-C connector.
I have to use a USB-A -> USB-C adapter to use my MIDI devices, as no regular USB inputs exist on the newer MacBooks.

I don't have the same issues with the same devices on my older iMac with USB-A inputs.
There is one more factor to take into consideration though; on the MacBook Pro I run MacOS 10.14.3 (Mojave) and on the iMac I run 10.13.6 (High Sierra).

Does anyone else experience similar issues?

I have an AKAI MPD218, M-Audio Oxygen 25 IV, and a Nectar Impact LX61+, and all three devices behave the same when using USB-C adaptors (tried several) on the MacBook Pro.

Just wondering if there might be a connection between this behavior and the use of USB-C on gear designed for USB-A connections or if this is something related to the built-in "Class Compliant" Apple Midi drivers included with MacOS X 10.14, or both... ?