Difference between 人和 and 仁和
They are not quite the same.

人和 is a reference to 天时地利人和, where 和 means "harmony" rather than "unity". So it means "people in harmony".

仁和 is "humane and harmonious", both are good social and personal qualities.

The difference isn't that important if we take it out of context. They are all positive words that fit well for a company name. 



Update. In answer to your last question: No. 

The naming style is quite common in 1930s. It might serve as a sarcastic device -- A company bearing such a beautiful name are acting so evil. But even this would be an over-interpretation. Every company wants a good name. If I am writing a 1930s novel, no matter what I believe, I would use the same naming styles.