Which one to buy one travel insurance for whole trip or two separate?

I am planning to travel to singapore for vacations in 2 months. i need guidance on travel insurance. if i apply for one now, and then coming october i got to go bangkok for a workshop i need to attend. will the same insurance be used ? or i shall require a new insurance?

Check if two insurance policies are cheaper or one long term policy. Mention reasons on the visit in the proposal form.