If it’s your Multiplayer Minecraft Server, you can copy your Worlds folder and then paste it into your single player save files pretty easily, and of course you can access the seed of any single player world by simply typing /seed into the chat bar.
How do you find the seed of a Minecraft server?
How to Find Minecraft Server Seed –
How do I find my multiplayer world seed?
You can then go to your multiplayer world, to see if the world looks the same by going to the coordinates that you checked in your singleplayer world. Enter the /seed command in chat and the seed will be displayed.
How do I find my realm seed?
How to access your minecraft CONSOLE and Find Your SEED
How do I change the seed of my minecraft server?
To change the seed you have to edit your server configuration file.
- On your Multicraft panel on the left menu go to Files -> Config Files and click on Server settings.
- Scroll down to the line where it says “Level Seed” and type your seed into the box.