Two Premium Bond holders from Wiltshire and Bedfordshire have scooped the top £1m prize in the March draw.
One winner, a man from Wiltshire, had owned just a few bonds since childhood, but then invested up to the maximum limit - £50,000 - seven months ago.
The second winner, a man from Bedfordshire, has £7,500 in bonds and this was the first draw in which his bonds were eligible to win a prize.
Jill Waters, retail director at NS&I, said: "The popularity of Premium Bonds is enriched with the moments Ernie creates and the great stories that are there to be told.
"This month sees a second win in the county of Wiltshire in three months and shows how an investment, which initially started with just a few bonds in childhood, has increased over time - reaching the maximum - and has landed the jackpot prize.
"Luck was also in for the Bedfordshire winner, winning the £1m prize with his initial investment."
NS&I, which operates the Premium Bond draws, urged those with old bonds to check whether they have won prizes.
There are currently around 1.4 million unclaimed Premium Bonds prizes, worth more than £58m.
In Wiltshire, there are currently around 9,000 unclaimed prizes worth more than £330,000.
Bedfordshire currently has around 5,000 unclaimed prizes worth more than £200,000.
Customers can visit the NS&I website at www.nsandi.com, download the prize checker app for free at the App Store or Google Play to see if they are owed a prize.
They can also write to NS&I, Glasgow, G58 1SB asking for their prize history (they need to include their name, address and NS&I number or Premium Bonds holder’s number.