Is it the insurance person asking?
I don't know the intricacies of these things. I could picture (rightly or wrongly) that each bond could say it covers the first $x of a loss. So if you have two $20,000 bonds that say that, and you incur a $30,000 loss, might only $20k really be covered?
And why get two bonds? I'm sure one for the entire amount would be cheaper than two smaller ones...