Well I guess I stand correctecd. I just went through the '54 restoration pack and sure enough duals are listed as an option on a 3/4-ton. I was sure they didn't offer that until the Task Force years.
The restoration pack is available online.
'54 Chevy Restoration Pack.
The wheels listed are 16 inch, which is different than the 18 inch wheels on a 1-ton dually.
Do you have pictures or yours posted online? Especially that show the wheels? Do they look like the 1-ton wheels?