Yes. There have been documented cases of tornadoes merging. See the link below for a video of this happening.
When two tornadoes merge, it is just called merging; there is no special term.
Tornadoes are least common in winter and autumn.
When two tornadoes merge they form a larger tornado. There is no special term for the product of such a merger. In most cases it is not even considered a new tornado but rather a continuation of whichever of the original two tornadoes was larger.
Tornadoes are least likely to occur in fall and winter.
Tornadoes can merge together, yes, and vortex physics predict that the combined tornado will be larger than either of the merging tornadoes. However, most tornado mergers involve a large tornado absorbing a small one, so the larger tornado is not affected very much.
When two tornadoes combine they simply merge to form a larger tornado. Usually it happens when one large tornado absorbs a smaller one.
A tornado and a hurricane cannot "combine" as they operate on different scales. It is fairly common for tornadoes to produce tornadoes.
When tornadoes merge they simply become one tornado large than either of the original two. It is an unusual occurrence and most of the time that it does happen it involves a large tornado absorbing a small one without being much affected.
Yes, of course there can be two tornadoes at the same time.
Yes. If two tornadoes collide they will merge to form one tornado.
When two tornadoes merge, it is just called merging; there is no special term.
Two characteristics of tornadoes are violently rotating winds and intense low pressure.
Tornadoes occur in all twelve months of the year, not just two. May and June are the most active months for tornadoes.
If two tornadoes come together they merge into one tornado.
There are multivortex tornadoes that at times can look like they are made up of two or more tornadoes
There were two tornadoes in the state of Washington in 2011.
There were two weak tornadoes in the sate of Washington in 2010.