> Is there a way to splice them next to each other?
Yes, but first you need to add empty space to one of the images, so the other image can be copy/pasted into it. The following procedure may seem like more work than it actually is :)
Open the first image in the Viewer/Editor and use Edit | Copy (Ctrl-C) to copy it to the clipboard. Also, take note of its height and width in pixels.
Then open the second image and use "Transform | Crop or Add Borders" to add enough empty space to your image to hold the other image (note: to add empty space, enter negative crop values in this dialog and mark 'add border').
For the next operation, it's best if you maximize your window and press F6 ('Fit All' zoom mode) so the entire image, with its added space, is visible on your screen.
Now use Edit | Paste (Ctrl-V) to paste the first image from the clipboard onto the large second image. Note that its initial position is in the upper left corner, but you can drag it with the mouse or use the keyboard to move it around until it aligns neatly with your original image (use Shift-Arrows for large steps, Ctrl-Arrows for precise steps). Press Enter to complete, then save the resulting combined image.
