Multiple membership upsell using online membership page with paypal standard records incorrect membership end date

Multiple membership upsell using online membership page with paypal standard records incorrect membership end date. It is also incorrect in the email receipt

Configured a contribution page:
1) With membersip settings enabled, having price sets (with checkbox as field type) enabled with multiple membership types (in my case 4 membership types , 2 types each belonging to different organizations).

2) PayPal standard as payment processor.

Signup for 2 memberships on same sigup page, the membership dates saved and shown in receipt are proper.

Upsell both the memberships, the membership end dates of both memberships are getting updated and shown in receipt are incorrect.

For eg:
There are 2 membership types TypeA (rolling , duration : 1 year) and TypeB (rolling , duration : 2 year)

• if i signed up for TypeA membership as of today: the start date is October 17th, 2012, the end date is October 16th, 2013.
• if i upsell the membership from TypeA to TypeB : the start date is October 17th, 2012, the end date is October 16th, 2017. (this end date is incorrect if should be October 17th, 2015)

Note: This happens only when we configure the membership sign up page with multiple membership types using price set, so that during sign up user is able to sign up for multiple membership types (belong to different organizations)