No they don't... But I don't think that you were wondering if they had the same MB, you were hoping to upgrade you present laptop.
Yes!!! There is a solution... I am a owner of an Inspiron 1526, been using it for two years... With todays updates (Windows/Office/Adobe), it is a really slow machine, the processor is outdated, it only has 1mb l2 cache... Here is what I did to keep this laptop alive. Bought a 1525 motherboard off Ebay. Bought a T7500 Core 2 duo cpu, with a 1525 heatsink for the cpu off Ebay. I spent a grand total of $23 bucks... This laptop now is great!!! I'm just telling you, everything else is compatible, it is the best $23 dollars I've ever spent... Before you go do this, realize that you will have to reinstall windows from scratch because the chipsets on the motherboards are completly different... Trust me, the difference is huge but you need to be tech savy cause the 1525/1526 laptop is not a easy one to take apart and reassemble... If you google it, you'll find a procedure to do the whole process...