One is enough for most travellers. Two bodies suit experienced photographers because they remove lens changes and provide a backup if one fails, usually a wide lens on one and a telephoto on the other. The cost is weight, expense, more batteries, more cards and more to protect, and two large cameras on a wet Zodiac get awkward enough to interfere with moving safely.
A second body should solve a real problem you've actually had. Bringing one because professional photographers often carry one is how people end up with a bag they resent by day three.
If your reason for a second body is avoiding lens changes, a single broad-range zoom solves the same problem for a fraction of the weight.