You can check number of them in "Inventory - Extra".
Speed Potion can be obtained from regional achievements and event achievements, some quest reward, event's final reward, daily reward, some offers, some event/main-story mine and some old event's repeatable.
There are only total 3 (1H) Speed Potion in this game that can be obtained only from Egypt story mine.
(72H) Speed Potion can be obtained only from regional achievements.
Speed Potion doesn't stack. It will overwrite the previous one.
|(1H) Speed Potion|
|(4H) Speed Potion|
|(8H) Speed Potion|
|(24H) Speed Potion|
|(72H) Speed Potion|
|(168H) Speed Potion|
|(?) Speed Potion|