How does a "Control Dispute" arise?

I was reading the OTC Markets glossary:

Control Dispute — A Control Dispute occurs when multiple parties claim control of a company. OTC Markets Group does not determine control or work to resolve the dispute. When OTC Markets Group becomes aware of a control dispute, our practice is to remove all control persons from the Company Profile and await resolution. Control Disputes are resolved when there is an agreement between the two parties or a court order confirming control by one party.

• How does a control dispute arise? How is it possible for multiple parties to claim control of a company? Isn’t the percentage ownership of a company obvious from the shareholder register?
• Since I know little about corporate governance: how is it advantageous for anyone to "claim control" over a company? What is the nature of this "control" if one succeeds in obtaining this "control"?