We need to update to the 9.2 runtime in order to fix a problem on a lot of PC's. Can the both 9.1 and 9.2 Toolkit runtimes be installed on the same machine or do we need to remove the 9.1 runtime first.
Thanks
If you have the SDK 9.1 Runtime installed and then install the SDK 9.2 Runtime on top of it, it will automatically remove the SDK 9.1 Runtime first and then install the SDK 9.2 Runtime. As for the runtime files themselves, the 9.2 Runtime will include everything the 9.1 Runtime had, but also be the most up to date versions of those files.
The individual SDK packages are separate installations. The latest SDK runtime supersedes prior ones - so for example, the SDK 9.2 runtime supersedes the SDK 9.1 runtime, but it includes the same files (often with subsequent bug fixes) and has no compatibility issues. It's generally recommended to use the latest runtime anyway for this reason.
Note that if an update is required, it will do it for you - you shouldn't need to manually remove the old one.