[R-SIG-Mac]bug in lm()?

[Christof Bigler]

After having used lm(), I encountered some odd results in the Darwin 
version (Mac G4, OS X Version 10.1.3). Then I tried out this (in the 
Darwin and the Carbon version):

> > dummy1 <- c(1:10)
> > dummy2 <- c(1:10)

Darwin version (1.4.0):

a)
> > lm(dummy1~dummy2)
>
> Call:
> lm(formula = dummy1 ~ dummy2)
>
> Coefficients:
> (Intercept)       dummy2
>   2.442e-15    1.000e+00
>
b)
> > lm(c(1:10)~c(1:10))
>
> Call:
> lm(formula = c(1:10) ~ c(1:10))
>
> Coefficients:
> (Intercept)
>          22

Carbon version (1.3.1, yes I know!):

c)
> > lm(dummy1 ~ dummy2)
>
> Call:
> lm(formula = dummy1 ~ dummy2)
>
> Coefficients:
> (Intercept)       dummy2
>           0            1
>
d)
> > lm(c(1:10)~c(1:10))
>
> Call:
> lm(formula = c(1:10) ~ c(1:10))
>
> Coefficients:
> (Intercept)
>         5.5
>

Are there any explanations, why one can get 4 different results 
(although just one is correct)?

Christof