Flying machine dupe glitch

When I play Minecraft 1.12.2 and made a specific flying machine fly with slime blocks, observers and Sticky piston while a separate application on my computer is lagging the computer. Blocks inside of the machine would every so often duplicate itself in mid-air so you would see a trail of flying machines appearing. I will put up a photo later.

 

P.s the "Affected Version/s" did not like me and I was forced to say what it says.