I doubt they really spoke to each other much. Large companies have two or three of everything going on because it's nigh-impossible for everyone to aware of everyone else.
If they did talk, I expect it would mostly be to decide on segmentation.
So far, at least from this outside perspective, it looks like Azure, Azure DevOps, and GitHub all seem to be talking to each other and where there seems to be external redundancy there seems to be internal reuse/recycling/consistency (some of which not always apparent). CodeSpaces for instance looks like it shares a lot of infrastructure no matter how you launch it (from GitHub or from Azure). GitHub Actions supposedly shares a core and a lot of code with Azure DevOps Pipelines.
Microsoft still seems to be quite coy on what the actual long term plan is, but from at least some appearances there seems to be one in this case. (I've heard lots of rumors but no easy to find reputable sources that Azure DevOps eventually gets eaten as a brand by the GitHub brand and an eventual (auto-)migration. I still don't know if I can trust those rumors, but that seems like one of the better options to me.) At the moment in the short/medium term it seems like Microsoft is trying to dual brand the same products to target different customer types.
Well yes and no, GitHub is increasingly powered by Azure (GitHub Actions and CodeSpaces as obvious examples), but like I said I've got the feeling that "Azure DevOps" is more likelier to be retired as a brand/product line than GitHub will.
You can tell that Microsoft absolutely respects GitHub as a brand and just based on raw public changelogs and available roadmaps there seems to be a lot more investment in labor and "spirit" in GitHub than Azure DevOps right now.
Again, there are nothing more than rumors at this point. Yet there was always something of an impression that when Microsoft's bharry retired the lights might go out on Microsoft's TFS/VSO/Azure DevOps legacy, and the timing of the GitHub purchase coincides with that idea that GitHub is a full replacement.
I've even heard some of how strongly Microsoft sales people are trying to encourage on-premises server installs to move to GitHub Enterprise (and away from legacy TFS products).
Many signs seem to be pointing to GitHub will be the last product standing (powered by Azure).
If they did talk, I expect it would mostly be to decide on segmentation.