Pictures from Earth
The ground-based images, provided in FITS format, were selected among
several provided to the mission after a call for interested amateur
and professional astronomers to obtain matching images.
The Proxima Centauri image was obtained on April 22 at 12:51 UT (8:51
a.m. ET) by Edward Gomez using a remotely operated 0.4-meter telescope
at the Siding Spring node of the Las Cumbres Observatory in Australia.
This is nine minutes earlier than the New Horizons image, relative to
Proxima Centauri time. The timing accounts for New Horizons being
nearly three light hours closer to Proxima Centauri than Earth when
the images were taken.
The Wolf 359 image was obtained on April 23 at 04:37 UT (12:37 a.m.
ET) with the University of Louisville 0.6-meter telescope located at
Mt. Lemmon Observatory, near Tucson, Arizona, operated remotely by
John F. Kielkopf (University of Louisville) and Karen A. Collins
(Harvard and Smithsonian Center for Astrophysics). This is 37 minutes
later than the New Horizons image, relative to Wolf 359 time. The
timing accounts for New Horizons being nearly four light hours farther
from Wolf 359 than Earth when the images were taken.
Source: http://pluto.jhuapl.edu/Learn/Parallax/Parallax-Images.php

Some background noise was left on this New Horizons image.
Several professional and amateur telescopes were used, so no spare LORRI camera could be used at different locations simultaneously.
But if the images made from Earth are of similar or better quality and resolution, all aligning may be done by digital image processing.
- selecting image pairs with sufficient overlap
- matching images by shifting, rotating and zooming operations
- aligning background and stars brightness of the image pairs
- resampling the images to get an equal resolution
- selecting equal frames sizes
Processing
The mission team processed the images to match those taken by New
Horizons.
Processing steps included:
Removing anomalously bright pixels (due to detector imperfections);
Removing subtle electronic noise;
Shifting the images to align the stars;
Removing bright pixels caused by cosmic ray strikes;
Enlarging the images;
Adding the images together to improve quality;
Adjusting alignment, brightness, contrast and sharpness
to match the Earth-based images
#NHparallax Post your Images
Using software and methods of their choosing, amateur astronomers can
combine their images with the New Horizons pictures, and post the 3D
parallax products on Twitter, Instagram or other social media with the
hashtag #NHparallax.
New Horizons contributing scientist, astrophysicist and legendary
Queen guitarist Brian May uses an OWL viewer to check out the stereo
images of Proxima Centauri he created by combining pictures from
Earth-based telescopes and the New Horizons spacecraft.
So no spare LORRI camera was used for images made on Earth. I found no information if a spare LORRI camera exists.
All block quotes from Johns Hopkins University Applied Physics Laboratory website.