I wanted to know if there is any contradiction when someone is learning several different instruments?

For example, I am learning to play piano . Would becoming a good piano player in any way hold me back from playing another instrument professionally?

P.S. Sorry i couldn't explain well
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One of the more dangerous combinations is piano and piano accordion. The similarity of the keyboard leads to a conflation of technique that results in "lowest common denominator" approaches.

The piano is a percussive string instrument featuring impetus-sensitive attack and rather fuzzy decay, the accordion is a continuous-tone wind instrument with an attack basically insensitive to key impulse and a very precise key release imprint that, through bellows inertia, also impacts the strength of the next attack, making leggiero articulation the core of fast play, and continuous bellows control the core of slow emotional play. You would not expect to change from hurdygurdy to violin without significant investment in bow technique, either...

In this case it is more the "similarity" of the controllers that is masking core differences. In a similar vein, few people are renowned for *both* piano and organ playing skills, even though harpsichord and organ is not all that uncommon as combination.

So when going for multiple instruments, it might be prudent to pick something which significantly differs in its controls. That way, you are less tempted to skip over basics that may make a difference in why people would rather hear you play a *real* instrument than a keyboard controller with sampled sounds of it.
The first thing to emphasise is that "professional" and "highly skilled" do not necessarily go hand in hand. The Sex Pistols were professional musicians, but you wouldn't use them as examples of how to play their instruments well!

It's also important to emphasise that *expecting* to become a professional musician when you're just starting is wildly over-optimistic. From all the people who start playing instruments, maybe 1 in 20 stick with it long enough that they can earn a bit of beer money playing in an pub band. Maybe 1 in 1000 are good enough to earn a living from it - and most of them will be working as music teachers. Something like 1 in 100,000 will be good enough to earn a living wage solely from performing.

You certainly will find that different instruments need different techniques. Synth and piano will need different ways of playing and thinking about the sound, for instance. That doesn't make it impossible to learn both, but you do need to remember that they are different instruments, and you can't assume that skills on one will always transfer. Even different examples of the same instrument will need time to learn their specific characteristics - on a piano, for instance, the hammer action can be radically different between different pianos, and it can take a few hours of playing to really get the hang of a new one.