Can I register an identical mark under different classes?

Identical marks can co-exist if the goods are different eg. LOTUS is registered by separate entities for goods such as cars, shoes and computer software. If LOTUS LONDON was applied for however, this would still be considered as similar to LOTUS.

In relation to your question on conflicting classes, an objection raised may only affect 1 class but not necessarily others. It really depends on the actual goods and services specified within those classes.