It is not the same since you will note be taking the 10% off the original price which is greater than the discounted price.
Example: An item is priced at $10.00 and if you take 35% off it would then cost 10.00-3.50 = $6.50.
But if you first take 25% off the 10 it would be 10.00-2.50 =7.50 and now 10%off it is 7.50-0.75= $6.75 which is greater than the $6.50 from the initial 35% off.
Therefore the advertisement of 25% then a 10% is acutally less than a 35% off the original price.