The short answer is yes, a trademark can have multiple owners; however, there are caveats to trademark co-ownership.
While not illegal, joint ownership of a trademark is not desired by intellectual property offices. The reason for this stems from the fundamental purpose of a trademark, which is to inform consumers about a single source of goods and services, which in the case of multiple owners would be ambiguous.
Therefore, if multiple parties wish to co-own a trademark, they must create a legal contract indicating joint ownership. Each party should also have some control over the nature and the quality of the goods and services.
Unless specifically stated in the contract between the two parties, the ownership of the trademark in question is equally shared.
One option for multiple trademark owners is to form a new legal entity specifically for the purpose of owning the trademark.