No, you can only have one website development project running at a time. This is because you have one dedicated web developer assigned to your account, and website development projects are complex and resource-intensive, requiring focused attention from a specialized professional.
However, you can have one website development project AND one website design project running simultaneously, since these are separate service categories with different team members (web developer vs web designer).
If you submit multiple website development requests, any additional projects will be queued and started immediately after your current development project is completed. Since projects typically finish quickly, queued work moves through the pipeline efficiently.