Originally reported here.

This appears to only happen with OptiFine. (Tested with OptiFine HD U E7)

To reproduce:

1. Place a lit campfire.
2. Go through a nether portal or use a command (such as CoFH's /cofh tpx <dimId>) to go to a different dimension.
3. Return to the original dimension, at the same coordinates. (Notice that the campfire is producing more smoke than normal)
4. Extinguish or break the campfire.
   -> There is still smoke coming out of the extinguished/broken campfire. Image

Notes:

• It only affects campfires that are within the chunks that are loaded on arriving in the dimension. Campfires in chunks that are not near the arrival chunks are not affected.
• The duplicate tile is impossible to get rid of under normal means. Placing other blocks or tile entities on top don't affect it. It doesn't even unload when its chunk unloads. The only way to remove it is to save and quit to title, then reload the world.
• Since the duplicate tile is only on the client side, it won't do anything like cook items or apply regeneration effects. All it will do is create particles. If the campfire it duplicated isn't lit, it's basically impossible to even tell that it's there.
• The duplicate tile entity is created with default settings - it is not loaded from the NBT of the actual tile entity. The effect is more clear on campfires that are signal fires: the actual tile's smoke will rise to signal fire height before disappearing, the duplicated tile's smoke will not.

So this isn't a Campfire Backport issue?

I did some testing and I would rule this out as a Campfire issue since it is mostly an Optifine issue.
With Optifine, every modded particle emitter seems to be having this problem:

Tested with:
-Railcraft Smoker (Railcraft_1.7.10-9.12.2.1)
-Campfire (campfirebackport-1.7.10-1.7.3)
-Encased Smoker (twilightforest-1.7.10-2.3.8.5-dev)

Only the Ars Magica 2 Particle Emitter did not have this issue but its render code relies on AnimationAPI.

I doubt it is fixable without some dirty hack or fixing 1.7.10 Optifine itself.

The duplicate tile is impossible to get rid of under normal means. Placing other blocks or tile entities on top don't affect it. It doesn't even unload when its chunk unloads. The only way to remove it is to save and quit to title, then reload the world.

In my case, after placing and breaking a few dozen campfires for testing, the invisible duplicate do eventually disappear on chunk unload.