I know that Avicii uses samples from his producers friends, not too sure about Alesso.

To create these kickdrums, there are a few ways - mainly relying on layering.

We'll start with layering two kickdrums up, one being a low end 'bassier' kickdrum and the other being a high end 'snappier' kickdrum.
To make these sound good, it all relies on the samples you've used.

Ok, so what you need to do is, cut all the high frequencies on the 'bassier' kick & cut all the low frequencies on the 'snappier' kick.
I can't tell you how much to cut because it depends on the samples you've used.

Ok, now you need set the volume of the samples to your preference so that they 'gel' together.

Now, send both of your samples to one send channel and use a compressor, this makes them gel together & sound 'tight'.
Again, I can't tell you what settings to use because it depends on the samples you've used.

You can boost the low end of the 'bassier' kickdrum & boost the high end of the 'snappier' kickdrum if you like, But - be careful with boosting, only boost a little.

Hope this helps, if you need anymore info. just ask :)