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yellow but different computer monitors can show colours that are slightly different to the real deal
Lying the test phials on their side isn't the best way to tell colour. You have the phials standing upright on a piece of white card or white bench, and look down into them.
My screen shows in your bottom picture, one is yellow , one is green. ( The top pic is useless because of the background.) If they are both from the same tank from the same time, that shouldn't be. As I've said before, unless someone has the same screen settings as your eyes, showing pictures for colors is not going to be 100% accurate. Showing pictures against anything other than pure white paper with natural sunlight is not going to give you an accurate reading either. The background is giving an influence to your test results as is any kind of unnatural lighting. ( Go to any home lighting store and look at soft white, sunlight and LED light bulbs, all the same wattage, and they will all look different. That's why you need natural sunlight for a proper diagnosis.)
Some people find it easier to look down on the vial to determine the color, some from the sides. Both are accurate when you use the proper background and lighting.