Got something like that in practice with backup recovery - IRL most probably the sequence of events leading to that discrepancy was different (not clear yet).

```sql
drop table enum_alter_issue;
create table enum_alter_issue (a Enum8('one' = 1, 'two' = 2)) engine = ReplicatedMergeTree('/clickhouse/tables/enum_alter_issue', 'test') ORDER BY a;

-- backup / move part aside or similar operation 
insert into enum_alter_issue values ('one'), ('two');
alter table enum_alter_issue detach partition id 'all';

-- schema evolution (enum get extended)
alter table enum_alter_issue modify column a Enum8('one' = 1, 'two' = 2, 'three' = 3);
insert into enum_alter_issue values ('one'), ('two');
alter table enum_alter_issue detach partition id 'all';

-- attempt to attach back all the parts (new generation and old generation)
alter table enum_alter_issue attach partition id 'all';

Received exception from server (version 21.9.1):
Code: 53. DB::Exception: Received from localhost:9000. DB::Exception: Type mismatch for column a. Column has type Enum8('one' = 1, 'two' = 2, 'three' = 3), got type Enum8('one' = 1, 'two' = 2). 
```
{
    Block res;
    for (const auto & column : getColumns().getOrdinary())
        res.insert({column.type->createColumn(), column.type, column.name});
    return res;
}
Block StorageInMemoryMetadata::getSampleBlockWithVirtuals(const NamesAndTypesList & virtuals) const
{
    auto res = getSampleBlock();
    
    
    for (const auto & column : virtuals)
        res.insert({column.type->createColumn(), column.type, column.name});
    return res;
}
Block StorageInMemoryMetadata::getSampleBlock() const
{
    Block res;
    for (const auto & column : getColumns().getAllPhysical())
        res.insert({column.type->createColumn(), column.type, column.name});
    return res;
}
Block StorageInMemoryMetadata::getSampleBlockForColumns(