Let me clarify, I am not suggesting that you simply give someone stock because they grumbled or feels slighted because 2nd round angels received more value for their investment. Maybe the 2nd round investors were simply better negotiators. There are a number of reasons that giving more stock was necessary. I am suggesting that maybe the first angels have abilities etc that could have helped to hold costs down etc. requiring the necessity to raise a smaller amount which would ultimately minimize their stock further diluting. This in effect results in greater stock value than if you would just take the total amount of money from additional angels.
Angels I have worked with have always been great and would not expect a "gift" of additional stock. That being said, if an angel had skills, products, or services that I otherwise would have paid more for, I worked with them to supply what was needed for far less $ and future stock options.
Experienced Angels realize that raising more money is often necessary and if additional money is not raised their risk on their investment increases exponentially. Further, most would have first right to increase their investment so they can invest and prevent their dilution as well.
Communication is the key and I was fortunate to work with good angels. I had their back and they had mine, hence we were in it together. They never expected to be given anything but because we communicated their skills and networks became readily accessible.