Lightroom does not natively export two different JPEG versions from the same source in a single export action. One export applies one set of settings to all selected files, so the built-in workflow is still two separate exports.

Common workarounds mentioned were:

• export once at full size, then use another program to create smaller web versions
• use Photoshop/Image Processor Pro for multiple output sizes
• use a Lightroom plugin such as RC Export Manager, which can run multiple export presets in one operation

So, in Lightroom alone: no. If you want one-click multi-output exports, you’ll need a plugin or an external post-export step.