I only can import ONE VIDEO p er sequence

Hello @BrendaFl,

Thanks for posting your question, and welcome to the forums. Your issue is that you are unaware of source patching, an important part of understanding how to properly "drag" (overwrite) clips to the Timeline.

Please engage the Source Patching indicators next to the track you are editing to. https://community.adobe.com/t5/premiere-pro-discussions/faq-why-does-audio-or-video-not-go-to-the-track-where-i-drop-it/td-p/3540610

That way, the clip will be overwritten onto the timeline's proper track—in your case, V1.

Common misunderstandings: proper use of editing terms can be important when getting help with troubleshooting.

• Import is a function of bringing clips into the Project panel (not the Timeline) from the Finder, Explorer, or via File > Import.
  • Typically, importing all your clips and graphics is done before beginning the edit session.
  • You can add assets along the way afterward, as they are needed.
  • After importing the footage, it's important to organize it.
• Overwrite is a typical edit you can get by dragging clips from the Project panel to the Timeline. An overwrite edit will record over (erase) any existing clips into the timeline.
• Insert is another way to drag clips into the Timeline when you want to drag a clip between two clips on the Timeline.
• Source patching must be enabled properly whenever you overwrite or insert (drag) a clip into the Timeline. If souce patching is not enabled, then the clip cannot be edited into the timeline.

Editing Assembly Workflow:

• When organizing a project (and before you begin overwriting clips into the Timeline), import all the clips you will need for the editing session into the timeline.
• (Optional, but common) After clips are imported to the project, organize them into folders (called bins). Label (color code) and add any log notes to the clips as you organize if you like.
• Make sure Source Patching is enabled on the proper tracks.
• Insert or overwrite the clip into the Timeline by dragging or using the Insert or Overwrite buttons or keyboard shortcuts (you may find this method is faster than dragging after you become more fluent with the technique).
• (Optional, but useful) Instead of directly dragging clips to the Timeline, you can load them into the Source Monitor by double-clicking them. This allows you to set In and Out points before editing these clips into the Timeline.
• Then, repeat this process until assembly is complete.

Please return with any questions you may have. Again, these are common issues. A Premiere Pro 101 course (LinkedIn Learning is recommended) would not take too long and would answer more workflow questions to help you move forward. As a former NLE instructor, I encourage you to try that. I hope the advice helps. 

Thanks,
Kevin