I can't see anyway how. The Mediterranean region, where Rome conveniently sat, was full of societies in which were in such close proximity to each other that technologies often spread either through trade or war. Metal has been used by Egyptians since 2000 BC. Don't you think 1500-2000 years later when Rome came to prominence, that basic technologies and metal work hadn't spread?

I do have an idea of what you're saying, and the closest thing that I can think of is the Spanish and the Mesoamericans. Mesoamericans had metal, they know what it was, and most importantly, they used it. They however, did not use metal on their weapons. They used metal largely for decorative and art purposes. Aztec swords usually comprised of obsidian, same with the spear and arrow heads. Native Americans in what is the continental USA used metal on an extremely smaller level.

Have advanced societies encountered others that didn't use metal? Probably yea. Did Rome? Most likely not.