I don’t think they are. Why are you asking?
mmm
For factual answers, here is A technical point to consider.
There are two aspects to effective filtration, stopping the small particles and letting the air through. Many articles focus more on the first point. Occasional articles do point out that imperfect fitting allows breathing around the mask, therefore bypassing filtration. I think it is also important to consider that a very restrictive mask substrate encourages leak around the edge of the mask. (In hospitals, they have experts to help fit the N-95 masks.)
So, wearing 2 masks may be counterproductive if they are not well fitted, in that it would cause more air to be unfiltered.
(It would still help, especially in preventing transmission outward, as many droplets emitted outward would still be deposited on the mask, which is a good thing. Just maybe NOT better than a single mask.)
There is a useful role for double masking.
A cheaper outer mask can be used to protect a more valuable inner mask.
Surgical masks are used to cover less common (well-fitted) N-95 masks to allow re-use of N-95 masks to extend hospital PPE resources. (We are STILL doing that, which is one measure of how NOT on the “other side” of this thing we are.)
You could wear a thin, stretchy, easily removable fabric mask over a surgical mask. It would hold your surgical mask close to face, minimizing air gaps. You could remove fabric mask after public contacts for later washing, replace with new one. Your surgical mask would stay “clean”* longer.
*“clean” is relative here, referring to Covid. It would still get damp and pick up your boy-germs (girl-germs for you ladies). So you would want to clean or replace that mask periodically as well.
This is something I notice in the videos and such where they show their O2 levels are fine while wearing 2 or more masks. If they are not sealing the mask to their face, air can be coming in through gaps along the sides and nose rather than through the mask. Air is going to take the path of least resistance. It’s not going to go through multiple layers of filtering material unless that is the only path it can take.
Proper fit is something that is totally being forgotten about in the messaging about masks. The good thing is that an ill-fitting mask still impedes exhaled droplets so others are protected, but the wearer is missing out on valuable filtering protection of their inhaled air.
Here’s an example to demonstrate the importance of good fit. Get a plastic cup or something and hold it tightly to your mouth such that when you breathe in, it produces a vacuum. Then hold it loosely or tilt the cup just enough to just break the seal to produce tiny gaps which allow you to breathe comfortably. Obviously none of the air is coming through the cup. Tiny slivers of gaps along the edges will allow massive amounts of air to pass through and you’ll have no trouble breathing. Keep that in mind when you’re wearing masks. If your mask doesn’t fit well, you’re likely breathing in massive amounts of unfiltered air.
Couple of things to add:
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I’m seeing some people wearing sanding masks which have a valve in them so that exhaling is easier - these are pretty useless as it means most of what you exhale is not filtered in any way.
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Telling people that the masks are primarily for the protection of other people is, in practice, a bad way to sell the idea. We should have told people that wearing a mask makes your penis grow, or makes your political opponents cry, or something.
They should have told Americans that Covid causes rapid weight gain.
Moved from GQ to QZ.
I will give you the benefit of the doubt and treat this like it is not a joke.
The reason the mask protects others from you is not the direction of the mask but the fact that it’s covering your respiratory holes. You are trapping potential virus at its source, reducing the amount that is shed into the air. It also does protect you, by filtering out some of what is already in the air. This is particularly important with covid-19 because it is very common for people with no symptoms to be infectious, unlike the flu, where generally if people have it, they feel sick and stay home.
See answer above. You further decrease the amount virus you broadcast but not qualitiatvie change in who is protected.
Well, true in my case. 
Hehehe
The fact that everyone who read your OP assumed it had to be a joke should give you pause to consider that perhaps the problem here does not lie with everyone else.
I understood the OP’s question just fine.
An offensive joke from my local republicans on a similar topic.
I’ve been married a long time. The only way my boy-germs get to meet girl-germs anymore is when the wife and I swap masks. Cleaning in between defeats that purpose. 
Maybe if we read the OP backwards, or better still, read it once forward and once back, then everyone will understand it.