Hi cameol8779899:
The only way for this to happen is if the first page of each chapter is using a custom master page.
New double-sided documents start with a default left and right master page. Anything you add to them (i.e., a page number) will immediately appear on all the body pages. To remove a page number, you have to add a custom master, remove the page number variable and assign it page to 1 either thought Format > Page Layout > Apply Master Pages or a master page mapping table on the reference pages.
In your scenario, you could either add the page number to the custom master behind page 1 as per Arnis, or revaluate page 1. Does it need to look different from all the other right hand pages? If it doesn't, you can assign Right/Left to body page 1 (again Format > Page Layout > Apply Master Pages), then delete the custom master. If it was assigned through the master page mapping table, then remove that reference from the reference pages, as well.
~Barb