Back Up Beds is an extremely small and simple mod. Back Up Beds tracks the last five (number configurable) beds you have slept in on the server, and in the event of respawning, attempts to place you in the last non-obstructed bed or respawn anchor you have used.
With Back Up Beds installed, you can set up a bed outside the entrance of a dungeon, sleep in it to set your secondary spawn point, and then respawn there if you die in the dungeon. Once you're finished clearing the dungeon you can simply break your bed outside the dungeon, and your next respawn will be at your previous bed, likely the one you have slept in at home. This makes Back Up Beds perfect for exploration and other adventure-themed modpacks.
