With regard to indirect buffers mentioned in the accepted answer...

`M-x clone-indirect-buffer` will create an indirect buffer for the current buffer. The name of the new buffer will have '<2>' added to it (or a greater number if you've already got duplicate buffer names). The new buffer is opened in a new window. You can switch back to a single window using `C-x 0` or `C-x 1`.

With `M-x winner-mode` you can easily switch between the two locations. `C-c <left>` / `M-x winner-undo` and `C-c <right>` / `M-x winner-redo` switches between window configurations. In this case the configurations will be positions in the two buffers viewing the one file. 

Note: the `winner-undo` and `winner-redo` functions work on a list of configurations. If the configuration is changed, e.g. moving point, then the current configuration becomes the head of the list and `winner-redo` is invalid, in this case `winner-undo` will bring back the previous position.

For the OP's situation this leads to the following process;

 1. Turn on winner mode `M-x winner-mode`
 2. Visit file (filename: File1.txt, buffer name: File1.txt)
 3. `M-x clone-indirect-buffer` (new indirect buffer name: File1.txt<2>)
 4. Make current window the only window `C-x 1`
 5. Find first edit location, make changes.
 6. Switch to original buffer visiting file, `C-x b` (default will be original buffer unless a switch to another buffer took place since step 3). This creates a new configuration for winner to switch back to.
 7. Find alternative edit location, make changes.

A switch to the previous edit location (windowr configuration) depends on whether a change is made to the window configuration between switches;

 - If a change is made switch using `C-c <left>` / `M-x winner-undo`.
 - If no change is made switches use `C-c <left>` / `M-x winner-undo` for back and `C-c <right>` / `M-x winner-redo` for forward.

A change is anything other than another `winner-undo` or `winner-redo`.