This issue is rather tricky to explain, but I will do my best.

Everytime I'm in-game, (i.e. actually moving around and such, not in menus), I need to press a key twice for it to take effect, when I've already pressed down any specific key. What this translates to is, If I press W and start moving forward, any other key I press after it, let's say Space Bar for jump, it doesn't work. Instead, I need to press the key I want to use twice, for it to actually trigger. So, in the end, If I want to jump, I gotta press Spacebar twice (jumping after the second press, and not the first).

In the past, and mind you this is a new laptop I bought three months ago, I had no issues with minecraft on my Desktop.

1. Press W to move forward
2. Press Spacebar once - doesn't result in jumping.
3. Press Spacebar again - It does jump.

This happens with any and every key. For example, the same thing happens If I press W and D. I need to press D twice to actually go right.
Another example. If I press A, I start going left, but If I press W, I need to press it twice to start moving forward.