Question: animate plots at different times while fading

As an example, how can I overlap the timing of these two pointplots in the same plot?

with(plots);
a := animate(pointplot, [[[3, 2], [2, 5], [5, 2], [5, 5]], transparency = A], A = 0 .. 1);
b := animate(pointplot, [[[2, 2], [4, 5], [3, 2], [3, 3]], transparency = A], A = 0 .. 1);
display(a, b, insequence = true, view = [0 .. 10, 0 .. 10]);

I want the second plot to appear 2 seconds later as the first plot is still fading away. 

 

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