I use Docker to build my .NET apps, using a base image provided by Microsoft (mcr.microsoft.com/dotnet/core/sdk:3.1).
In addition to .NET Core SDK 3.1, I also need .NET Core SDK 2.2 inside the same container.
How can I extend the base image and install .NET Core SDK 2.2, without breaking the version in the base image? I noticed that Microsoft does not use a package manager to install .NET in the base image.