Learn English – verb meaning “to make similar”

The most appropriate term I can think of is composite, used either as a noun or adjective. NOAD provides some excellent accompanying examples:

composite

(adjective) made up of several parts or elements:

• (esp. of a constructional material) made up of recognizable constituents:

  a new composite material—a blend of plastic and ceramic resins.

(noun) a thing made up of several parts or elements:

• a composite constructional material:

  the next decade may well see the introduction of more designer polymers and composites

Since composite refers to several elements, not just two, you could use it in your example this way:

... between the two different sites in the composite blend

using the word two to specify how many elements there are.

The answer provided by Kris, however, is more technically appropriate for the specific example you mention. However, combining this with your suggestion, binary composite is certainly an excellent alternative. Binary mixture is also technically correct, as all composites, amalgams, blends, etc, are simply mixtures.

In the United States, this practice is called weaving (sometimes "weaving in and out"). Here is some text from the overview to a Georgia Tech study on the practice:

The effects of weaving are some of the least understood aspects of traffic flow. Along the I-85 corridor, weaving regularly occurs between the HOV (or HOT) lane and general purpose lanes, and between interchanges. Because vehicles typically accelerate/decelerate when weaving, the capacity of a freeway network is reduced. Not only does weaving impact effecive capacity, it affects the safety of motorists. Due to safety concerns, attention will be given to weaving zones where there is a high speed differential between weaving lanes. It is important to note that illegal weaving along managed lanes also has the potential to affect safety and capacity.

Now, it seems logical that a person who engages in this activity should be called a weaver, but it is doubtful that this meaning would be understood without explicitly introducing the topic of traffic weaving.