1.

Let's go and practice.
Let's go to practice.
Let's go practice.
(Are they the same?)

2.
Come and see me.
Come to see me.
Come see me.
(Are they the same?)

3.
They often help wash the dishes.
They ofthen help to wash the dishes.
(Are bothe the same?)

They are all correct and each group of sentences mean about the same.

However, the first sentence in number 3 is much more commonly used.