Similar logos can turn up for several reasons, and some are so similar they make us do a double take. Originality is normally a key goal in logo design. When a brand's trying to stand out and make itself known and memorable, it doesn't usually make sense to look like another brand. Beyond potential legal issues, it would go against the idea of trying to forge a unique brand identity.
Of course, there are brands that intentionally use similar logos to try to create an association with a popular brand or even directly pass themselves off as a better known company. But while obvious, intentional rip-offs are widely condemned by the creative community, things aren't always so clear cut.
