In my experience the option 'append' sometimes works and sometimes doesn't - could anyone explain the below to me?

sysuse auto
encode make, gen(make2)
* example 1: append works
table var foreign, stat(fvpercent rep78 ) sformat("%s%%" fvpercent) nformat(%6.0f) nototals style(table-1) name(t1)
table var foreign, stat(fvpercent make2) stat(mean mpg) sformat("%s%%" fvpercent) nformat(%6.0f) nototals style(table-1) name(t1) append
* example 2: append doesn't work
table var foreign, stat(fvpercent rep78 ) sformat("%s%%" fvpercent) nformat(%6.0f) nototals style(table-1) name(t2)
table var foreign, stat(mean mpg) nformat(%6.0f) nototals style(table-1) name(t2) append

Thanks in advance!