Does export template mono contain standard?
No, but Mono export templates can run projects that only use GDScript. It's recommended to use the standard editor and export templates in this case, as standard export templates are significantly smaller.
If not, can godot (mono version) has both templates and how switch between them?
You need to install and use the standard editor to use standard export templates.
And can I have both version of godot on my ubuntu ?
Yes, you should even be able to run both at the same time :)
They will use the same configuration file, but this shouldn't be an issue.