If I have once, I reckon I have a hundred times?

I don't understand what exactly "if i have once, I have a hundred time" means in this context in red below.
Does "if I have once" means that if one is said to be the one like that (considered (by others) to be the businessman who brought in good slaves), then he can claim that he hears that a hundred times?
Thank you:)

" It don't look well, now, for a feller to be praisin' him­self ; but I say it jest because it's the truth. I believe I 'm reckoned to bring in about the finest droves of *** that is brought in, — at least, I 've been told so ; if I have once, I reckon I have a hundred times, all in good case, — fat and likely, and I lose as few as any man in the business. And I lays it all to my management, sir ; and humanity, sir, I may say, is the great pillar of my man­agement."