Learn English – the word for two objects that one comes after another one

One (somewhat archaic) option is

Cleave -- "to split or divide by or as if by a cutting blow, especially along a natural line of division, as the grain of wood." (Dictionary.com)

This doesn't explicitly create exactly two parts, but generally if you split something with a single blow, you'll only end up with two parts.

An common phrase that does explicitly specify the number of resulting parts is to split (something) in two

You are either aligning your blocks (that is, arranging them in a line) or juxtaposing them.

The latter (juxtaposing) works better if you have only two blocks; for more than that, go with aligning.