my worlds are "lobby" (this is where i set the spawnpoint, more like a spawn world only and they will just use a command to teleport to "world"), world, world_the_end, world_the_nether everytime a new player joins it spawns first for a second in "world" then to the "lobby" where they keep on seeing "Joining world" twice. in my server.properties file the level name is set to "world" however when i changed it to lobby, they spawn directly to spawnpoint i set. Although i want "world" to be the default world on my server. because "lobby" is supposed to be exclusive only for spawning point, event areas. etc. could it be possible ?
Get a /setspawn plugin, if you already have, use multiverse to /mv setspawn. It also might be a plugin doing that.