Clicking 1d8 weapon in character sheet for example, game rolling 2d20?

Title basically explains issue, on the character sheet, the character will have for example a one-handed battleaxe, thats 1d8. But when I click it, the game rolls 2d20? What am I missing here?

Which character sheet?  Can you show a screenshot of the roll? If it is an inline roll please hover over it so we see the details of the roll.  Can you screenshot the settings of the character sheet's attack? 

If you're using the 5E by Roll20 sheet, I beleive the default for a weapon attack is to roll the attack with advantage (so it makes two d20 attack rolls), but not to automatically roll the damage. That sounds like what you're describing. Go to the fourth page of the sheet (the gear icon) and in the top-right, change the "Roll Queries"  and "Auto Damage Roll" pulldowns to suit your preferences. You can also change the defaults for these for any new sheets created in a game in the Game Settings (before launching), but that won't apply to existing sheets.