Has nothing to do with Canon EOS 70 or whatever camera.
Colors are weird after stacking as RGB aligning is Enabled by default.
For better results, you should disable this.
See:
http://www.clarkvision.com/articles/...essing.basics/
and scroll down to a chapter called "Image Stacking with DSS".
Colors can be changed afterwards by Photoshop / Lightroom or Darktable.
Roger Clark (of this site I mentioned) has more tips on AP processing on the same webpage.
A very important example: do not set wrong color balancing.