Yes...You are correct that hens "generally" lay eggs that are similar in shape, size, color That is not always true though. There is some variation. If you trap nest you may be suprised how much it varies from day to day, but if you trap nest you will also get to where you know what hen laid each egg. When I lived in Texas we had 12 coops. I would put 1-2 Black Copper Marans, 1-2 Cream legbars, 1-2 Basque hens, Breda, etc in each pen so that I could see who was laying each egg for daily egg records. Some times my wife would collect eggs then she would show me an add and ask which pen it came from. Many times I would be 100% correct. Don't tell my wife, but I had an advantage. I knew which hens had laid the day before and how many days they had laid in a row, so I always knew which hens were due to miss a day. That greatly increased my accuracy when we played the which pens is this egg from game.
What line are your Legbars from? The egg color comes from the breeding. I have seen lots of people with the newest imported "Rees" line have hens lay the greener eggs. The older Legbar lines from the 2010-2011 imports generally have bluer egg. So...you may have two wirdo CLB. Since they lay the same shape color, they may be sisters or other wise related.
I have got 4 blue eggs over the last four days. I am very happy to finally be getting eggs again. The three months with no eggs while we made our move from Texas to Oklahoma about killed us.