Well they do have 2 types of batteries. Only one of them is dual purpose on the AGM chart.
Even the 6 volt AGM deep cycle has CCA rating.
Intimidator Starting and Cycling Service batteries
means high starting and moderate deep cycle power.
Ideal for boaters that want high cranking power and
still enjoy dependable power for more electronic
accessories.
The Sams club battery is the 8A31DTM but it is branded as Duracell 31DTMAGM heavy duty deep cycle.
Intimidator Heavy-Duty Deep Cycle batteries have
more fish-finding trolling and accessory power. Ideal
for heavy deep cycle demands, with moderate
starting power. Provides advanced protection against
the typical deep discharge of extended trolling use.
East Penn / Dekka AGM batteries