Theory / Approaches for combining beams of the same wavelength?

I've seen reference to multiple diode arrays, or to the combining of two (same wavelength) beams. I'm wondering how this is done?

I understand the concept behind using dichroic films to combine different wavelengths, but I don't yet understand how you would combine two (say 1W 445nm) beams to create a more powerful single combined beam.

I've done a bit of research to figure this out, and came across some approaches requiring polarized beams, but it seemed somewhat complex. Is there a practical approach used frequently for hobby-level laser builds, that might not break the bank?

You need to use a Polarised Beam Splitter Cube (PBS) and have the 2 diodes horizontally & vertically opposed (polarisation?)

Heres the build I done.

http://laserpointerforums.com/f48/pain-beam-combining-i-see-red-54506.html

There's also a technique called "knife edging". You search for it, and you shall find info.

Here is an example of knife edging on a big scale.