NO!!! I got 5 chicks and two turned out to be roosters. They were raised together so i figured they could live together. Sometimes they would fight but i thought they would be fine together... but i was wrong. One morning as i went out to feed them i found one of them dead. The other rooster had killed it.
I would actually look at other possible causes for this. Everything from an illness to a wandering cat. I've had problems with foxes in a subdivision I used to live in, snakes, cats, raccoons, and even a hawk.
Usually when they are raised together, they will have no problem. Yes, they may fight over hens, but they establish a pecking order and that's what they live by.
The problem with keeping roosters together isn't so much how bad they fight amongst each other, but how bad they tear up the hens. I adopted four mixed-breed bantam hens a few months ago, and NONE of them had tail feathers. They were also missing plenty of feathers around their necks. The roosters that they were living with had just pulled the feathers out so much, in an attempt to mate with them.
I brought them back and placed the four hens with two bantam roos - one frizzle, one mille fleur. They have since grown their tail feathers back and their necks are mostly covered again. And even at the 2:1 ratio.... they made it worse by going broody after just a month of being here! That kept the roosters from breeding at all! But everybody was still okay. And they all live together in a giant 25ft by 17ft pen with a netted top.
However... placing a BABY rooster with a full-grown flock will likely get the baby killed, no matter what. You need to add them when they are similar in size. If you add an adult to a flock, he'll fight with the existing roo for a while, but with 20 acres, you have space for him to get away and that should be fine. Eventually, he'll blend in with the main flock. But unless you keep them all separate, your hens are likely to lay mixed-breed eggs anyway.