Sellers selling on the ECOs may have common places of business, especially if their goods are stored in a shared facility operated by the ECO. This shall result in the same additional place of business being registered by multiple suppliers. Is this allowed?

Yes, this is legit and allowed. Any GST registered taxpayer can declare any premises as his place of business if he has all the documents supporting his claim.

There is NO specific restriction about a place of business being used by multiple GST registered suppliers. Hence, multiple suppliers and the ECOs can use the same storing facilities and declare this premise as their place of business.