The question as asked is vague, and may want to be narrowed down, but here is my understanding of the question, and my best swing at answering; you appear to be asking 'What conditions would lead a medieval culture aesthetically similar to Europe's to develop independently on two entirely separate continents, and just how likely is that to happen?'
My answer - there needs to be large reserves of metals, especially iron but also copper, tin and gold, and a history of metallurgy. There needs to be a large and robust trade network, and domestic horses or similar animals. There needs to be a substantial winter in more than half of the available landmass. There needs to be a history of militaristic empire that pushes society towards designing standardized weaponry and protective structures like castles, walls and towers. As long as both continents meet these conditions without overlapping with one another, it feels realistic that both continents might have arrived at similar medieval eras at around the same time in a sort of parallel evolution.
However, it is important to understand just how diverse this image is, and has to be in order to exist in the first place. When you say 'medieval Europe,' you are including a vast world of differences. For nearly 700 years, muslim kingdoms controlled large portions of Spain; Italy was a mess of oligarchic and democratic city states fighting one another in wars mostly funded by trade with India and China and largely fought by mercenaries, some from as far away as england; Other areas might have been ruled by kings, or by popes, or by councils of nobles who elected their ruler; The boundaries by which we may now define 'Europe', 'Asia' and 'the Middle East' would have been drawn very differently, and those differences would be felt in the way people dressed, the design of their architecture, and the weapons and armor they used in combat. And that's just Europe - There are plenty of other parts of the world that had medieval eras, from Africa to continental Asia to Japan. Both of your continental areas must feature this level of diversity to be fully believable. There is no such thing as a medieval Europe without the backing of a larger world to compete with, trade with, to conquer and be conquered by.
Also, even if they are at a similar level of technology, their cultures will necessarily be different in big ways. Religions, languages, and value systems all will have developed independently. Certain things they will have in common - technology such as bows and crossbows, levers and pulleys, clockworks, as well as the use of gold as currency if it is available, all of these things have been known to develop independently in separate cultures, as they draw on natural facts (tension, gravity, and the fact that gold doesn't tarnish and thus retains its value). On the other hand, other technologies such as gunpowder, glassblowing or silk, depend on the presence of specific resources and the understanding of how to utilize them - and if one continent has one of these and the other doesn't, it will spell out a rather large difference. Even something that seems as small as what natural fibers and colors of dye are available to them will affect the way they look and feel.
In short, as long as you do some research and make your two continents feel enough like they have truly different histories, both in terms of the people and the animals and plants that live there, it can still feel realistic that both continents might feature medieval feeling societies.