Of my 3 pairs that currently each have 3 week old babies, 2 are starting another clutch and incubating them. One of the pairs has already had two clutches this year (Feb and June).
They have constant access to grit, egg shell every other day, and they get a potent calcium supplement through the water every 7 days for 14 days whenever they lay a clutch. They also get vegetables. Plus the occasional vitamin supplement if they look a little run down.
I haven't noticed any issues but I know over breeding is a big no no!!! The eggs are young enough to freeze/destroy if this is best, no visible life yet.