Answer

Samvatsari and Ganesh Chaturthi do not always fall on the same day.

They often come close because both occur around Bhadrapad Shukla Chaturthi / Panchami period, depending on the Jain calendar tradition and local calculation.

The most recent time before a same-day occurrence would depend on the specific calendar year and local panchang being used. Sorry, I can only provide information that is clearly established within Jain tradition.

Explanation

In Jain Dharma:

• Samvatsari is the most important day of Paryushan, especially in the Śvetāmbara tradition.
• It is observed on Bhadrapad Shukla Panchami according to the traditional Jain calendar, though practical observance can vary by tradition and regional calendar calculation.
• Ganesh Chaturthi is generally observed on Bhadrapad Shukla Chaturthi in the Hindu calendar.

Because these are based on lunar dates and panchang calculations, their civil-calendar dates can shift, and in some years they may appear very close or even be observed on the same civil day depending on timing.

Takeaway

From a Jain perspective, the key point is that Samvatsari is the sacred day of forgiveness, pratikraman, repentance, and saying “Michchhami Dukkadam.” Its date should be followed according to one’s Jain sangh, guru-paramparā, and local panchang.